Just thinking a little more about the offer:
- I'd be surprised if you had more autonomy at a Big4 sub-manager level
- How sure are you of that fast-track promo? Can they give examples of other people where this has actually converted (presuming thay won't commit this part of the offer to paper). Any chance you could go to manager now rather than later?
- Very sceptical about the chances of moving to PE or Strategy off the back of IT due diligence. Again, what more info can you find on this?
- That's quite a big paycut (maybe up to £20k after bonus?)
- Big4 on the CV is always helpful for the long term (although of course depends what your long term goals are..)
As regards your current company:
- Sounds like if you stick it out until you're promoted you'll be in the manager slot and in a completely different game, so that may address any role quality concerns
- In which case maybe the timing of your promo is really the main/only issue? When is the next round?
Difficult to say, but I think I'd stick it out until the manager promo is resolved one way or the other and then look again. However, if you think that, even at manager level, you'd be unsatisfied at your current company, maybe it's time for a change now.