YES I do. I used these carboys for several years when I ran a Ferment on Premises. Here are the problems that I can think of.....
1) They will scratch if you stir aggressively, especially with a drill, or use a brush for cleaning
2) Must be very careful if using a vacuum for degassing
3) They stain with red wines eventually. (I used the chlorinated pink powder cleaner to remove some/most of the stain. Make sure you rinse VERY WELL afterwards.)
4) Require an odd size bung (#8 or #8.5 I think), but you have the bungs already.
Positives...I never broke one in 6 years of winemaking, and believe me I dropped a lot of empty ones. I would regularly try to carry too many empty ones, and sooner or later some would hit the comcrete floor. They are pretty close to a true 23 litres (ie 6 US gallons).
Steve