I've no experience with IVI I'm afraid, but have done PGS
I miscarried a chromosomally normal embryo (from my second cycle) and so we knew the problem was the uterine environment (ie me).
We did PGS for diagnostic reasons as much as anything, because if we'd transferred an untested embryo and the cycle failed or I miscarried again, we wouldn't know if we'd cracked the uterine environment but the embryo was a dud, or if the embryo was normal and the uterine environment was still the problem
We had our 4 frozen embryos tested and all 4 were abnormal. So we'd have done up to 4 FET and all would have been destined to fail - and because I'd mc a normal before, we'd have assumed that as statistically at least one of them should have been normal (I was 34 at the time), that the problem was me
We then did another round and did PGS and had much better results - 6 normals!
Unfortunately we still haven't cracked the uterine environment, as we put a euploid embryo back in Sept and it wasn't a viable pregnancy
But we know the problem is the soil and not the seeds - and obv desperately hoping that if we can get the soil right, that a good seed will flourish
Good luck x