GR8 PLUMENG,
I took both the HVAC and Fire Protection (passed). I thought that the Fire Protection was much harder than the HVAC due to the number of codes that you have to study and also the Fire Science portions, which are covered in a Fire Protection Degree. One person I know is switching from HVAC to Thermal because he thinks that the Thermal test is much closer to the material that you learn in school. As opposed to the HVAC portion which has about 50% of the test on HVAC Applications/Equipment. I previously worked in an HVAC/Plumbing/Fire/Electrical consulting firm and I took the HVAC test after 2 years and although I passed, I struggled because I did not have very much experience. After I got more experience and I looked back on the problems, I found that the problems were a lot easier. Sorry for the long post, but my recommendation is to stick with the Thermal exam due to the reasons above. I don't recommend taking the Fire Protection exam and concur with your assessment. Let me know if you have any questions.