I've also read opinions from Switch owners who are playing Bloodstained and they're saying it is fine with no obvious issues, even in hand-held. There was a patch released the day before it became available so perhaps some of the issues in the review copies are already dealt with. From what I've read the slowdown issues are from certain areas later in the game so maybe they haven't go to those places yet. I think they will fix whatever is wrong with it but yeah these things should be optimised and ready to go at release. I will get it one day but not at full price.
I've had a good week or so now with Cadence of Hyrule and I absolutely love it. If you're a fan of the snes era Zelda games and/or rhythm games then this is a must. It's far more forgiving than Crypt of The Necrodancer which I found really quite difficult. It looks great and the music is superb.