On the point of the SFC, and esspecially slowdown and few sprites on screen at once. The key thing to remember about the SFC/SNES is that they sacrified the processor to keep costs down, but also left the door open with the expansion pins on the cartridge edge connector. The SNES equipped with some of it's best expansion chips is certainly nothing to be taunted. The SA-1 certainly fixed the slowdown issues, as could the SuperFX. Even the C4 chip helped with handling sprites.
So definitely don't belittle the SNES. It's a very well designed system with plenty of potential. And that goes for the PC-Engine too. Sadly though it's business and not every developer had the time and experience to make certain things a reality for our classic systems. But I'm pretty sure that both the SFC and PCE are capable of some of the things we dream.
Games I'd have liked to see for PCE:
Street Fighter II' Arcade CD-ROM - I liked the HuCard version. It stands up well but the music certainly could have been nicer. I'm not picky which version of SF2, but any done fully exploiting the potential of the PCE+ACD would have been awesome.
Mortal Kombat Arcade CD-ROM - No home system ever got this one right. Genesis lacked color depth, memory for graphical detail, and sound quality. SNES had the potential for the color depth and sound, but we all know how that turned out. PC-Engine certainly had the color depth needed and with the CD-ROM for audio I imagine something pretty good was possible. Plus with CD-ROM storing graphics the animations would be fluid and not cut down for a cartridge.
Teenage Mutant Ninja Turtles (Arcade Original) Arcade CD-ROM - This would have been awesome, esspecially with 4 players via the multitap! This one truely would have been amazing.
I'm sure I could think of more. Thinking about this also makes me think about what could have been done on the SNES with a good expansion chip and CD-ROM attachment.