I'm using some trekking/butterfly bars on a Trek 750 and these bars are pretty compact and don't offer a lot of space. For various reasons, I'd like to try twist shifters on this setup (3x7). If I stick with the Shimano STX rear derailleur, I have four options:

1) Sram SRT-400 Gripshift (stock shifters)
2) Sram MRX Gripshift
3) Shimano Revoshift SL-RS35
4) Shimano Revoshift SL-RS45

I have #1 on it now. These shifters are the OE shifters from 1997, and are less than precise. They shift with a rather unrefined "clack" and aren't very satisfying to use. They do work, though.

I've used #2, but in 1:1 flavor with a Sram rear derailleur. I've never used the 2:1 versions compatible with Shimano. The 1:1 versions are VERY smooth and enjoyable to use. To anyone who has used both: do they feel about the same?

Does anyone know the difference in #3 and #4? It appears that most RS45 units have a silver cover vs. plain black. Are there any mechanical differences between these? Are the RS45 better quality than the RS35? My daughter's Raleigh Alysa has the RS35s, and they work just fine, and do offer a better shift feel than my stock SRT-400 shifters.

Any thoughts or other ideas are appreciated. Thanks in advance.