Asked to lateral within the first year?

Currently sitting at a lower tier BB. We just completed a deal with client X. Long story short I have a good relationship with said client and they're willing to work with GS/MS so I've been offered to move banks.

However, it's under the year mark of my analyst stint. What's typical to ask for (if anything when moving up): like if my time spent at my current firm counts towards their timeline, having them pay for my clawback from sign-on, etc?

Also: more of a rant, but I feel guilty leaving because I really do like my team and my assumption is that our relationship will be destroyed. Is it worth moving up in name to a team that I know less well for a culture that I know to be great right now?

Edit: not sure about PE yet …