Regarding heat, I'd say if that's normal for your guitars then they should be okay. I think drastic climate changes are probably worse than a constant-but-uncomfortable temperature, in general. Also, if they were in cases that helps a lot with protection from the elements.
I have my own question... I recently got a good deal on a used 2x12 cab from GC. However, now that I have it home I feel like it might be way more than I need. I heard that 2x12 sounds better than 1x12, but I'm wondering if the trade-off in size is really worth it - especially considering my lack of skill and such. But on the other hand, a 1x12 is only about $80 less expensive, so that's tempting me to keep the bigger cab and just deal with the size.
Thoughts, opinions?