Hard to say if they would be of the exact same quality because it kind of depends upon how healthy the parents are. That being said...
If you select a boy and a girl plant grown from regular seeds of the same strain and pollinate them then yes theoretically they should have the same basic genetics but each plant started from seed could be of a different phenotype.
If you are cross pollinating two different strains then all bets are off but that does not mean you should not try to cross them. It’s just that the outcome is as yet unknown. If let’s say you have two strains you like and they make babies then the babies should have attributes of both parents. Common wisdom would dictate that if you have 2 strains that are good then why wouldn’t combining them also be good?
In the past many crosses were done in order to shorten flowering times like crossing a sativa with an indica so it finishes in 9-10 weeks. This is why there’s so many hybrids out there.
Don’t be afraid to do a seed run but always try do it with regular seed; feminized seed can carry over hermie traits.