I agree that SM is not a fad. But, SM every time? Not me. There are times when I think each one has an advantage. So, I'd pick one depending on the specifics.
Most of the time, for me, I roll up in the parking lot, put my wing and BP on my BM doubles, stand them up on the tailgate of my truck, put them on my back, walk to the boat, sit down in my bench spot, and shrug them off. It's a lot easier than carrying 2 individual cylinders in my hands. My friends with SUVs do the same thing, so a pickup is not a requirement for this.
Also, I use 120s for BM doubles. I think the 120s are probably too long for me - and certainly too long for some people - to use as SM cylinders. I am using 100s for SM. So, it seems to me that there is an advantage to BM doubles in terms of the amount of gas you can carry (conveniently). Most of my tech diving friends started with BM 100 doubles and most of them seem to have eventually concluded that 100s aren't big enough for the tech dives they want to do and have gotten themselves bigger cylinders. Going bigger in BM is no big deal. Bigger in SM does seem like it has the potential to be more of a problem.
And, if you are carrying 4 cylinders (2 bottom gas and 2 deco gas), which is really easier to deal with in the water? 2 on your back and 2 on your left side (or even 1 left and 1 right), or 1 on your right and 3 on your left? Sure, you can do it in SM, but it sure seems like it is EASIER (in the water) with 2 on your back. Maybe I'll change my mind on that when I am more experienced in SM.
My goal is the Thomas Hume in Lake Michigan, at 145ft (very pretty wreck that went down in 1891, very well preserved). I'm Great Lakes wreck obsessed and have been for something like 25 years. My wreck class with limited penetration is this weekend. I've already been diving some Great Lakes wrecks.
