Dion and Spyder Robotics are GREAT! I recently ordered and received in a record 3 days a Herpstat II thermostat. The process start to finish was painless and extremely easy.
The customer service was second to none, as is the thermostat itself. I would highly recommend a Herpstat or any Spyder Robotics to anyone in the market for one.
I currently own a Helix 1000 in addition to the Herpstat and while the Helix is a nice product, it's comparing a Cadillac to a Chevette in terms of options, accuracy, and overall quality of the product. Just my two cents for anyone that cares to hear it. :D