I replaced the Coleman Mach in my Mini-Lite with a Honeywell RTH111. There's also a programmable version (RTH221?). The don't support two speed AC fan, but if you install a single pole single throw switch, you can make it switchable. Or just pick one of the speeds (I can't tell much difference between them anyway.) See attached pics.
#2: SPST switch installed. This needs to be an "ON-ON" type. Note 3 openings and "Gas/Electric" switch opening on right
#3: 3 openings cut into one opening to make room for SPST switch. I also had to open it up into the Gas/Electric switch opening
#4: Shows how it goes back together.
PDF: Shows the old wiring and the new wiring.
Note #1: Instead of installing the small SPST switch in the T-stat, you could install a standard RV type rocker switch (JR Products #12625) in the wall next to the T-stat. I may yet do this after I get some experience with it.
NOTE #2: There's also a digital version of the Coleman Mach, but it's a bit pricey and isn't programmable, but would probably be a more straight-forward replacement. See here: http://www.amazon.com/Comfort-Colema.../dp/B00B1SAL54
The RTH111 was about $20 and a couple bucks for the SPST switch at Radio Shack. The digital version's about $5 more.