I've always believed in the SD2SNES.
Well, not always. When ikari_01 first started talking about it on nesdev back in 2009 when I was using a SNES Powerpak, my reaction was more along the lines of "pssh-yeah, right". And then, a year or two later, he had some working prototypes that ran games and worked with some of the DSPs, and I was a skeptic no longer.
I took him at his word that it could handle GSU-1/2, but I was still skeptical about SA-1. People have made me hopeful off and on about it, with this thread contributing both at various times, lol. I'm still hopeful there will be a limited implementation (or several game-specific limited implementations), but I'm not holding my breath, as much as I love the SA-1 games. I consider it kind of weird that S-DD1 isn't implemented yet though. This is one where I don't even care if it's remotely accurate, just as long as it decompresses the damned graphics at least as quickly as the original chip so I can run Street Fighter Zero 2 and finally ditch the silly Neviksti Star Ocean rom.

Edit:
I'm not denying the cart is excellent, but the prob with carts is replacing the batteries is a pain in the butt, costly, and more wear and tear constantly ejecting and inserting carts over and over. The Super NT cart slot isn't quite flush (they do wiggle slightly, but remain stable). SA-1 would be nice, that's all, but again, not holding my breath.
I agree, and the SRAM thing is huge when it comes to SA-1. Not only does it apply to Marvelous and Super Mario RPG, but until recently, I didn't even have a way to back up the SRAM on those carts (thanks, CopySNES!). CopySNES still doesn't allow writing SRAM back to the cart, but I'm hopeful it will eventually. At that point, maybe I'll preemptively replace my Super Mario RPG and Marvelous (and probably Jikkyou Oshaberi Parodius) batteries with battery holders for easy future replacment and finally feel okay about playing these games on real hardware, despite the remaining wear and tear issues you mention (hey, at least there is less of that than we used to inflict on our SNESes and carts!).