I have also been looking into compressors to supply air bags and pxrb and who know what else.
The concensus on the Kilby is that it is an excellent and well made continuous duty, belt driven compressor.
Oasis makes a continuos duty, mil spec electric compressor that is also excellent, but also just as expensive as the Kilby,
ExtremeAire is an excellent contniuous duty (150 psi)compressor, at about half the price of the Oasis and Kilby.
Air Zenith had some problems early on with bad parts for awhile, but they took care of their costumers very well and made good on the bad compressors. It is also a well made, fast, and easily reparable, electric compressor, and is quite affordable compared to the others.
ViaAir has a whole line of HD and Medium duty compressors that they have been making for a long time, and while they eventually may need replacing, so can anything and they are an GOOD value;
The most important thing to think about is pairing CFM and DUTY Cycle with tank size and actaula air needs.
ALSO, the more CFM and extreme duty cycles mean bigger motors and wires and physical sizes, except for the Kilby, which of cours runs off our beloved CTD
I will probably buy an ExtremAire or Air Zenith. Kilby only if I win the lottery. :-laf
Here are some links for info--
http://www.air-zenith.com/pdut_detail.asp?cateid=9&id=5
VIAIR 400 Air Compressor, VIAIR 400 Compressor, Viair 400C, Viair 400H, Viair 420C, Viair 450C, VIAIR 450H, VIAIR 460C Air Compressors
01. ExtremeAire 12 volt Compressor
Oasis Manufacturing