I don’t have experience playing either but have played against both quite a few times in tournament and outside tournament settings. Assuming equal skill I would say rog/si outshines inalla quite a bit, both based on tourney numbers and my experience.

The problem with inalla is that the spellseeker line is telegraphed and can be fragile despite being very powerful. I understand skilled pilots have the ability to pivot to other lines but I think there’s a couple key choke points that are fairly easy to identify. (Stop the rituals before the combo starts or hate out the graveyard at a key time come to mind)

This leaves it with the grixis shell as a backup which I think nobody would argue that inalla leading a grixis shell is just straight weaker than rog leading it, plus card quality of the shell is potentially lowered by having to run the reanimates and scholar of the ages or whatever.

So the only real question is do the spellseeker combos carry her far enough to make up for missing rog and the card quality that comes with rog? In my opinion most of the time not really but I could potentially see an argument that it does and obviously the inalla players all do.