how does this sub pm offer look like (in london)?

I think the terms are good, but the bigger question revolves around netting risk / what team you are joining. Think its night and day difference if its an established large team that has been at a big-name platform together for a substantial amount of time vs. smaller / newer team at less established platform. 14% vs. 12% payout is a small difference in comparison to 15% vs. 50% netting problem / team dissolution in the next three years.

I have never had to make a call like this one so hard to opine on how I would handle, but I do know multiple people have done the switch and run into netting / team issues in the first 1-3 years. While they may not have regretted the decision bc they want to more seriously pursue buyside rather than sellside, they certainly have found themselves in substantially worse compensation situations than if they had opted to stay. FWIW, 6-700k annually in London actually pays for a great quality of life and to a much greater extent than in Manhattan so its not an obvious choice. You can also be patient, its not like you won't get this look again in the future - if anything you'll probably get one with even better economics in a few years time.