To justify my vote of "Yes, tried and still using them", I just have to say that I lend out hammocks fairly regularly. I've also had camps of more than a dozen people trying hammocks, but not having their own. Basically, I need lots of 'loaning gear'.
On my personal (nobody else gets to use) rigs, I wouldn't let SlapStraps anywhere near them. I've used them and decided that I've no use for them on my hammocks, but they still get used by others. Therefore, yes, tried and still using them...sort of.