I have one of their 2500 watt models. It will be for sale soon too.
I like the design in the M class better. Not same board as the old ST's... though those are great too. I have seen alot of blown up ST's but I think people where doing stuff they should NOT do with them... like .5 ohms daily with shitty electical and letting the amps slide around in their trunks etc...
Either or is a good choice if that's what you got to pick from.
HMM ampguts had them with the same board, but I recently worked on an older ST-1500D and I don't think it had that board in it. Maybe that wasn't the model number.... Boy memphis had so many different models in the last couple years it's get confusing. Either way none of the ones I worked on were all that bad, but I hate the drive boards in them, but they do work, just don't let them come loose or if the outputs ever blow be ready for a nasty job rebuilding the drive boards in the old ST amps.
16-ST1500D or 16-MC1500D was the model number or so I thought.... But I swear it was a different board...
The 2500 I am talking about is the newer style with the light up M in the center. Like the 4K, but smaller.