Well let me see if my recent experience in upgrading will be of any help. I had a real old SM008 that I got started smoking with. Love it, love the entire smoking thing. BUT what was a problem for me was I had to cut briskets and slabs of ribs in half. And I made my wife aware of that. Also tough for me is she isn't that much of a meat eater, but love that most of the product coming out of it had been rendered fat free and tender. SO besides taking her shopping for some things she really wanted I told her if I got the bigger smoker I could get this cold smoke baffle and with that smoke salmon and cheese and make her her favorite, smoked whitefish (a spread).
I'm pretty blessed and was all ready to get a SM025 but really wanted something bigger - 18x18 shelves and the IQ4 controller. Well I found a SM150 about an hour from us and got that. My old smoker, we were having a bunch of work done on the house we rent by our next door neighbor. And every time he came over I cooked for them. So we did a deal where he got the smoker for some of his labor. I got the 150 for $1400.00 - and a bunch of hotel pans, tongs, wood and other stuff for $60.00. This thing needs some serious cleaning but otherwise it's really wonderful. And I got the cold smoke baffle on the way. We're going to Sam's Monday and I'm getting the salmon and will also make her gravlox with one slab of salmon and smoked salmon with the other... And you know somewhere down the line the wife is gonna come home with some new shoes or some THING she just had to have and I'll be a good sport and STFU about how much it cost...
Good luck.