I belive the long adapter's advantage is indeed as added support for the longer SSDs, but, I disagree that it generates heat since the longer part (with that copper lining where the SSDs are secured) acts like a secondary heatsink, drawing heat away from the SSD. Also, it can't generate heat, as was mentioned in the discussions, it doesn't have a chip, so there's nothing on it that generates heat. The only thing what generates heat, therefore, is the SSD and the surrounding components. The SSD is also located next to one of the fans (at least in most MBP models) so it does get partial cooling from the vortex/vacuum created as the fan sucks the air around it.Long adapter should no longer be used nowaday. Except when you are planning to use 2230 or 2242 ssd.
It generate more heat due to less available space for air. And it's not suitable for two sided ssd (although most of new ssd is 1 side)
Sintech is known to work, but they are NOT necessarily better than other options (pricier, yes. better, not really) . And they FAIL every now and then also just like any other adapters (or ssd - it's human made after all) . They just have a benefit of being the first one available around in 2013-2014 time.
And we are in 2022 now.
I've also mentioned that Sintech might just be a rebranded OEM (they all come from China), so it's basically the same as the other unbranded adapters. These OEMs will either work or fail, though most of them do work than otherwise.