The UV created by the flourescent bulb is used to excite the phosphor inside the bulb. I would expect that little to no UV escapes the tube under normal operation. Plus glass is not transparent to UV. However, quartz is transparent to UV. That is why quartz halogen bulbs have to have a glass filter to block the UV. That is also why metal vapor lamps have a separate glass bulb around the arc bulb, to block UV.
Regular glass is partially transparent to UV, and I wouldn't count on a 100% efficient phosphor and completely uniform coating along the inside of the envelope. Difference in heat can easily be measured with an IR thermometer, and the inherent increased efficiency of the fluorescent system (lower wattage, more energy converted into light) logically suggests a lower heat output. What other factor, besides UV, would break down the plastic so much? If you have a look at some exit signs, the fluorescent ones fall apart much quicker than incandescent or UV... I've broken a couple of covers on fluorescent ones because the plastic became so brittle from burning 24/7.
I'd like to see your source for claiming that quartz-halogen bulbs MUST have a glass filter. Other than PAR and sealed MR-type lamps, a lot of QH lamps have no such filter. Especially with MR16s and PARs, I think the reason for having a sealed unit is more for protection of the fragile envelope from moisture and debris, and to contain the fragments if/when the lamp blows.
Depending on the type of enclosed fixture we're taking about, have a look at LED PAR/MR lamps. While LEDs probably won't replace our general workhorse bulb, they are great for directional lighting--and the latest batch have color temperatures in the range of halogen.
