+1 for the Sharpsky pro, as Collin pounted out the sharpsky has temperature compensation as well as inbuilt dew heater controller. The sharpsky is beautifully engineered and support from Dave Trewen is excellent. I did a bit of a write up on it when I bought mine.
http://www.iceinspace.com.au/forum/s...d.php?t=112059
The sharpsky site
www.sharpsky.net