If you're only playing premiums in the early levels you're definitely missing out on some spots to gain equity, especially when you move up in stakes as your currently doing now, most of the regs have such a solid late game that we're forced to play more pots in the early game. I had a similar approach to you a while back, but i've since changed up my game and i'm much looser than normal in the early game, even in the mid-low stakes. The rationale is that most of the bad players either bust out early, or gain a huge chip stack, I want to be the guy busting those players early, and i feel i play the big stack better than most going into the mid-late game. Also, since most of the "meh" breakeven regs are playing that tight early game, we can exploit them by opening up more. So as games get tougher, we find differant ways to beat them, the classic tight early- aggro late 4 years ago would have netted a tidy 15% ROI, nowdays, you'll be lucky to get 2%.
And think about this too, do you really think your BVB shoves are going to get respect from regs late if you've been playing tight early? Hell, even bad players will now call looser on average than they used to, the whole setting up an image thing is long gone, so we may as well just open up earlier. Of course we need to be able to play solid postflop then, and we're likely to get 3bet/played back at a little more often.
Anways little off topic but relevant to your situation i think .
As for the betsizing, it seems fine to me, it's a little easier to get stacks in, but then we lose a little bit of pot control and stuff postflop, in reality i think 3x is fine. I was doing something similar at the 10/20 level at stars, It's much easier to get the stack in by the river if your raising to say 4x at this level. However once past that, i feel 3x is fine, it's still very easy to get stacks in by the river, and we don't lose as much when we say raise in late with AK, fire flop and get check/raised, overall i think 3x is probably better, i can't be bothered to do the math on that one.
Late game 2.5 seems to be the standard, but i'm quite happy making it 2.25 x or even min raising once the blinds get super high, especially at Full tilt where there isnt an ante, min raising can be fine in the High blind mid game.