This is just my opinion, anyone that disagrees please chime in but since there seems to be no mucus, no difficulty breathing and no wheezing then I do not believe you should suspect an RI.
Can you elaborate a little on her behavior? It doesn't sound like any disorder or problem that I am aware of.
I have 2 Helix DBS1000's and I think they are awesome. Yes that would be a great option to use for your thermostat. That is a proportional thermostat and I think its important that you know the difference between a proportional and ON/OFF types of thermostats.
You can read about the difference between the 2 types here: http://www.reptilebasics.com/thermostat-faq.html
My recommendation if you want a proportional thermostat is a Helix or Herpstat spyderrobotics.com/products/herpstat.html(have both, love both) and a Ranco if you want a ON/OFF type