What's so terrible? Serious question.
I don't foresee changing slides, but it would be nice if the locking blocks on 17's, 19's, 45's, 34's etc. were all interchangeable so you could if you saw a reason.
I personally think the 19 sized RSA is going to be more punchy/sharper cycling than the 17's, so would prefer that if picking a long slide option, but it's in the level of noise to overall performance.