I would not make too much of this "base up" stuff.
I have a few restaraunts as customers, and they all have CFL's in their cooking hoods. This is surely a location of elevated temps; being inside a "jelly jar" fixture makes sure it gets warm inside. The CFL's, according to my customers, far outlast conventional bulbs.
Likewise, I have a number of CFL's mounted horizontally, in open 'keyless' bases. Some CFL's last; others crap out inside a month.
I spoke with a man who has been in every factory (no kidding) that makes CFL's. His opinion of ALL of them is that they are pretty sloppy manufacturing facilities. I suspect that CFL failures are almost all due to poor quality control. You simply won't get the "beast and the brightest" when your manufacturing philosophy is "quickest and cheapest."
