There are a lot of factors here, it would seem that 700 watt element should be enough to get the temp up to 250º, my MES 40 is older with 800 watt element and has no problem getting 275º empty. When you add food depending on the load, the climb to set temp (about 225º) can take 1-4+ hours depending on the load size, obviously the larger the load the longer to achieve set temp. The reason for this is 2nd law of thermodynamics "heat always goes to cold". Thus your meat is absorbing lots of BTUs of heat, so empty the smoker gets to 250º in say 20-30 minutes, loaded with meat it can take hours. This is one of the reason I am HUGE on preheating the smoker, the colder the outdoor ambient the longer the preheat, if the smoker hasn't been preheated and say you simply turn it on add your wood for smoking and then add the meat when smoke has started, all that metal is cold thus absorbing heat, this means it will take longer to get to set temp (225º).
In my MES I noticed the difference by keeping notes on smokes, I noticed that recovery to set temp after opening the hatch was a lot faster after 3 or 4 hours of smoking than say 1 hour. So instead of having two cold or partially cold things to absorb heat btus (meat & cold metal cabinet + metal racks,etc), I could eliminate one by preheating. Even when the outdoor ambient is 70+ I still preheat just not as long. The newer MES with 1200 watt element would of course heat up everything faster because of more BTUs but again preheating would be still be beneficial.
Hopefully your Smoken-it has possibly a defective element, and a replacement would allow you to achieve temps over 214º.
