They are very good, I ran a zx1100 with one in the banjo bolt of the rear caliper, it may not be a recomended repair but it was 100% fluid tight.Helicoil type insert kits are cheap enough, but the timesert types are very expensive, which is a pity as they are a better job imho. Its a wonder no one has come out with a cheaper version.
Danger of jamming a VGT mechanism with large debris. I think even a small piece of debris hitting the turbine which could be doing in excess of 100,000rpm is cause for concern, anything that could compromise the balance of the assembly is undesirable. Melett for instance will instantly reject any warranty claim if there is evidence of foreign object damage, including on the nozzle assembly.
your point is valid in the past i my opinion would have been much the same, but ..... if there are potential warranty issues thats brilliant as it means it's new and therefor someone elses problemtho i have seen meany more issues and damage espectaly to turbos from people trying to do the job "to properly " imo do your best to minamise any stray swarf but disturbing an otherwise good head gasket or turbo isn't something i would do for the fun of it.
on a well used VNT id much rather let a bit of ali swarf blow though it off boost when the turbo is just ideling i give myself very good odds of getting away with it. takeing them off usally involves a whol lot more hasstel and risk of damaging it and more bolt stud issues
I can't think of any reason why it would be not recommended; a helicoil in ali is stronger than the original thread.They are very good, I ran a zx1100 with one in the banjo bolt of the rear caliper, it may not be a recomended repair but it was 100% fluid tight.