I noticed your post about 6 months ago. Since no one has responded, I finally gave into temptation.
We sell quite a few insect chambers. These are very similar to the chambers we supply to the pharma industry (with some modifications). We have a 7 year warranty on the thermoelectric assemblies. When the thermoelectric assemblies do go out, they can be replaced in about 10 minutes with a screwdriver by anyone with an ounce of mechanical skill and a ladder- so these insect chambers are really intended to last for the lifetime of the foam insulation (greater than 20 years). Typical refrigeration chambers aren't as simple. The thermoelectric units are not affected by the insect activities.
Since the temperature needs of insects are moderate, the cooling needs aren't that great. In this situation, thermoelectric cooling excels in efficiency. Our units tend to run about 4.5 amps @110 volts. Competitors can run up to 8 amps @208-220 volts. This can be a dramatic decrease in electrical usage and heat put into the lab. There is a sample of cost savings on our website...although to be honest, rarely are our customers interested in electrical usage cost savings.
Where I would not recommend thermoelectric cooling: areas where temperature is not controlled (warehouse, outside areas). Since the cooling capacity is less, these units will have a rough time when temperatures outside the chamber are greater than 15ºC higher compared to your set point of the chamber interior. Additionally, if you plan on having great lighting needs you might want to gravitate towards a refrigeration based chamber. We have seen a great shift in our customers switching from 32 - 96 watts of fluorescent lighting to 20 watt LED lights in a thermoelectric chamber and being very satisfied.
Finally, these units tend to be quieter than refrigeration models, especially in the smaller sizes (<50cft). Also, we usually set the units not to run the thermoelectric cooling at higher temps - making them almost silent at higher temps.
FYI We also make refrigeration based models & use refrigeration systems in our insect rooms.
Call us if you have any questions. I can give you a list of folks that recommend us.