The first thought that crossed my mind about Texas moving to the SEC is this: Texas has only nominally competed in the B12 the past 10 years... why should I think Texas can compete in-- much less be quasi-dominant-- in the SEC?
The expectations of Herman-- after Strong had, arguably, left the Texas cupboard partially stocked-- were only met if one expected Herman's upper, rather than Strong's lower, mediocrity on the field.
Put another way, Texas hasn't rebuilt playing in the B12 and the SEC competition won't speed up that rebuild-- unless Sark is the real deal and spiffies-up Texas' performance pre-2025.
IMO, the only slight advantage Texas has extracting themselves from the quagmire of the B12's 'lesser' team strength is that few SEC schools have the deeply ingrained, visceral hatred for Texas than say, traditional opponents like Baylor, Tech, TCU or OSU (all of whom always play over-their-heads when playing Texas).
Texas' historical record vs. SEC teams seems to support this, perhaps, only advantage Texas has going in.