I have used the MarHyde for 15 years now. I have never had scratches
come back to haunt me later. I did my own car about 4 yrs ago and it had
a lot of hail damage, no scratches so far.
The trick to not getting scratches is to let it cure before sanding.
I let it sit 24 hrs, wet sand it smooth then wait another 24 before painting.
I also over reduce so it sprays better, it also gets down in the scratches
better and does a better job when reduced a lot.
If someone is getting scratches they're usually rushing the job
and not allowing enough curing time.