The SM025 is what I have...I love it and recommend it highly
...I may sell it in the future, but just to size up!
The vent is not adjustable, but the unit does very well with heat and humidity control (ie no waterpan, etc needed)
Not sure how long the heating element lasts, though I do know that in the last several years they have upgraded the element and it has worked well for me so far...
The big benefits to me are: crazy insulation (you can cook in any weather), made in USA, unbelievable customer service, and great temp regulation