In reply to stp:
I work in construction and with fellow workmates often muse " how did we manage before " thunderbolts " or concrete screws. Easy and quick to fix, and removeable.
I use them for temporary fixings when bolting routes.
For permanent climbing bolts they may have the disadvantage that stp suggests of coming loose.
Also not readily available in stainless, it may be that SS is not hard enough for the cutting threads.
Personally, I think they could be ideal for short term bolt positioning on new routes.
The stress of cutting the threads will test the rock quality. The position can be changed if the first choice is not ideal, sometimes routes need to settle down if the initial rock cleaning is not 100%.
A quality SS or titanium glue in can then be used as a permanent anchor in the re drilled out hole.
The big negative to the last paragraph,of course, is that they are not climbing/PPE/CE rated.
So far I have placed them on slate and limestone.
My bolt extractor device easily pulls out 12mm though bolts.
Attempts to pull test the thunderbolts ( on slate ) have ended with a stupidly stretched Petzl hanger.
The thunderbolt stayed put, quite encouraging.
So, quite a good question, Ruth. Worth some further investigation, I agree.