Nice birds! Great color for no rub in an electric smoker, too...they look good enough to eat!
A soup can will have a lining in it, as well as the coating on the outside of the tin can...if either of these got too hot from a boil-dry condition, that could be suspect for toxins breaking out into the smoke chamber, though this would not be very likely in an electric smoker unless the thermostat failed to shut down power to the heating element and chamber temps went sky high...another scenario would be grease fire on the element. Hmm, thing is, in either case, I think you're dinner would be toast...er...burnt birds.
If you take a fairly sharp knife (lock-back or fixed blade) or tin snips, you can cut out the top of an aluminum can pretty easy. Here's the thing I never understood about the can chicken method: what about the dye or ink on the outside of those pop or beer cans? How about lined beer cans (keystone or coors...other brand...can't remember which)? What temp do these substances begin to off-gas and create toxins?
If there is a possible risk to using them (the various types of cans), you'll have to weigh that risk yourself. I haven't used the can cooking method for quite some time...funny thing is I have 4 can-chicken holders and have only used 2 of them, just once or twice, and never used them again...that's been three ago, I think. But, I'm more into the open grate smoke myself.
I digressed...anyway, some things to consider.
If you want to brine, look for non-enhanced birds (all natural), or they will already be injected with a solution which will hamper your attempt to get anything from your brine. Also, look for a brine recipe and method from a good source. Pops6927 is the first that comes to mind for a good brine, then Tip's Slaughter House Brine and Rubs for Poultry is another, just off the top of my head...there are many more here on the forums. I have done a few poultry brine recipes myself, but not that often.
The whiskey barrel smoke chips is a pretty stout smoke for poultry. It's an oak cask, which is charred inside, then has liquor aging in it for years, so, you gotta like the liquor to be able to get a flavor and aroma that will be tempting to your senses. If you like JD, maybe there was too much going on in the smoker with the sweet red wine in the water pan and JD/oak combined? Oak is a heavier smoke flavor and aroma, also, but is likely the reason for that marvelous color on your no-rub birds...it's capable of producing a very deep color on smoked meats.