201er, if a controller says "keep your speed up" without giving a specific number, they just want you to go as fast as you can safely can. If that will be much below your filed cruise speed, it might not hurt to tell the controller what speed you will do, so that they know what to expect. I don't know what the rules are in the US, but in Canada, the lowest speed we can legally issue a jet is 160kts and when using speed control for approach sequence, that is normally the speed we give to jets and turboprops to the FAF. So if you have a piston doing 90kts on the approach with other aircraft following, you need a LOT of extra room. If you can do 150kts or better until past the FAF, you'll fit in just fine, but at least for me, that is only reasonable/safe if I'll be in VMC when the time comes to slow down.
Pet peeves as a controller:
1. Pilots not listening. Everyone misses a call here and there (me included), that's not the end of the world, but if I need to call someone multiple times and and it's the same every time I transmit to you, I'll get annoyed.
2. If I've vectored you off course and then tell you direct XYZ and you turn to re-intercept the original magenta line instead of entering a direct to from your present position. The most common occurrence of this for me is VFRs going from CYTZ to CYKF, we have them follow the Lake Ontario shoreline until they are clear of the arrival/departure area for CYYZ and then tell them direct CYKF. If they turn to go back to the magenta line from CYTZ to CYKF they end up heading at YYZ arrivals or departures.