This may have been posted before, but I changed out my thermostat today (5 year maintenance interval for thermostats in my family). I found that you don't really have to take out the alternator to take out the thermostat housing. After I popped the serpentine belt off the alternator, I removed the top bolt and was able to just pitch the alternator forward enough to get my hands in there with a gearwrench. The problem with removing the entire alternator is that it is a pain in the rear to line up the bottom bolt again. At least for me, my casting flange of the bottom bolt and the alternator was a tight fit. (I did pull out the bottom bolt but found afterwards I didn't need to pull out the alternator entirely).
Also when I refilled my coolant, I used Zerex asian formula. To my best understanding, it meets ALL requirements of Toyota Pink and it's chemistry is even classified in the 2007 Matrix manual as appropriate. The manual does NOT say to use only Toyota Pink; it just says to use borate free, etc.....
I completely disagree with the Vibe manual that says Dex-Cool is ok. I just changed a thermostat for my Mom's CR-V today as well. It had a mixture of Honda blue and Prestone Universal in the system, and the thermo was caked with a hardened green slime. Not sure it's the 2-hea, but given the history if Dex-Cool I won't be going near it in any vehicle I own.