First off, I do have a Smokin-It #3 and have owned it for about 1.5 years now.
I will do my best to answer your questions below based on my experience with the smoker.
1. How far apart is the spacing of the racks. My MES 30 they sit about 4" apart so I'm wondering how the Smokin-It compares.
The default rack side rails are about 3" apart and have room for five trays. Smokin-It recently released a new 9-rack side rail for the #3 that I did purchase. I also purchased 5 seafood racks because I like to smoke large quantities of jerky and snack stix. This distance between trays on this optional side rail is about 1.5 inches. Essentially, they just took the standard 5 rail assembly and added another rail between each of the 5 shelves to get a total of 9. This is well worth it in my opinion because it gives you so much flexibility where you want your racks.
2. I have come to love using an AMZN Pellet smoker inside my MES sitting right next to the heating element/smoke box. Will that fit next to the element/smoke box in the Smokin-It 3? I realize I may find I don't need to use the AMZN pellet smoker, but I like to have the option.
I really don't think you will have the need for the AMZN with the Smokin-It smoker. They put off plenty of smoke during the smoke absorption period. Smoke can only be absorbed until the meat gets to about 140 degrees internal. So any other smoke is just piled on top and can make the meat bitter.
For low temp smokes like Jerky or cheese, I use the optional chip screen and chips instead of chunks. But for my normal smokes I only use chunks and have never wanted for more smoke.
3. I like to fill the water pan in My MES 30 with Apple Juice which catches the drippings and absorbs the smoke and makes what I laughingly refer to as "the love juice" which makes a really tasty finishing sauce/aju. Will a water pan or foil pan fit anywhere inside the Smokin-It 3 without taking up one of the 4 racks? It doesn't look like it.
I use a water pan filled with Cider/Beer/Soda/Water/etc in virtually all of my smokes with the exception of Jerky, fresh sausages, and poultry. I have never used the "love juice", but that sounds like a very interesting idea.
4. One thing I would LOVE to do but just have never felt comfortable with is overnight smokes. Get it started, monitor for a little while and then go to bed. Living in an apartment I just always worry about "what if something happens?". I'm curious if I should be worried about that and if the Smokin-It 3 is up to that task.
The overnight smokes will not be a problem at all with the #3. For virtually all of my longer smokes for Pork Butts or Brisket, I start smoking around 10:00PM-12:00AM and go to bed and sleep like a baby knowing that my meat will be at the right temperature all night long and be awesome the next day. I do have a Maverick et-733 that I remotely watch the temps with, but that is only for curiosity sake and for monitoring Internal Meat Temperature. As far as the amount of smoke and worried about your neighbors, with a very small hole on the top and bottom of the smoker as the only inlet/outlets, they do not put off a lot of external smoke. This is the main reason that you do not have to periodically add wood and can get by with so little wood to begin with. You will typically only use 2-6 ounces of wood depending on the meat that you are smoking.
5. When I bought my MES 30 I had to return 2 separate units because the gorillas at UPS damaged them. How is the packing job on the Smokin-It? Anyone had any issues with damage in shipping?
The units from Smokin-It are double-packed and I have only heard of a couple of issues with shipping and all were immediately taken care of by Steve the Smokin-It owner. These smokers are truly build like tanks and the main reason why I sprung for the #3 verses the #2. I do not plan on buying another smoker for 15-20 years.
6. And last, with either the Smokin-It 3 OR the MES 40 they both use a 1200 watt 10 amp element. I think my breakers at my apartment are 15 amp ( the switches have a "15" on them), but I'm not 100% sure, could they be 10? If they are is that ok or am I pushing it? As a renter, I'm not big on taking chances.
My smoker works absolutely fine on my 15amp breakers and I have never had a problem.
7. In your second post, you mentioned being concerned about flare-ups. When I hear the term flare-up, I think about the juices from the meat starting on fire and charring/burning the meat. I think you were misinterpreting some of the posts, because I have never heard of any issues with flare-ups with the Smokin-It smokers.
What many of us have experienced and Old Sarge mentioned above is what is called the "Belch" that can occur when your wood combusts. I have had this happen and it did not affect the results of my meat at all. The "belch" is mainly evident on the #3s because of the large heating element and how quickly it brings the smoker up to temperature.
There are however, 2 main ways of avoiding this. The original way that we resolved this issue was by ramping up the temp instead of going full blast at 225-235 right away. Instead, start your smoker at 150 for 45 minutes or so, and then ramp up to your main cooking temperature (usually 225-235). Recently many have been foiling the bottom half of their wood chunks and going full blast from the beginning. Using either of these two methods will reduce or in most cases totally eliminate this issue.
And like Old Sarge said, even if this does happen it is well contained in your smoker and there is no danger externally and definitely no need for a fire extinguisher. In fact if it ever does happen, I would recommend not even opening the smoker and let it ride.
The one thing that I found though is that the foil method does not work for low temp smokes. For low temp smokes, you would want to use the ramp-up method.
As a final note, I know you have a post or two on the SmokinItForums community and we are very happy to have you over there. So, you already know what an active and vibrant community we have over there. I have belonged to a lot of similar forums over the years from vehicle forums to computer and household devices and the SmokingItForums site is probably the best one that I have ever belonged to.
This ended up getting kind of wordy, but hey you were looking for feedback and I got on a roll. Can you tell that I am excited and happy with my smoker? :)
Feel free to ask more questions or PM me here or on the SI forums site and I will do my best to answer any other questions that you may have.