I've been finding out about Celebrity recently.

If you want their anytime dining (I think they call it Select dining), you need to prepay the gratuities. I haven't done this because I wish to mop up my OBC for this.

It's also a bit more advantageous to not prepay as that would cost us £107.67 per person for a 14 day cruise while paying at the end of the cruise would cost $10.25 x 14 = $143.50. Using today's exchange rate of 1.616, $143.50 is equivalent to £89.

It's only a £20 or so difference which is neither here nor there (especially when we don't know the exchange rate of the actual transaction now) but I can't see us using $400 of OBC since the TA has thrown in 10 bottles of wine for the 2 of us and there's a free dining experience at a speciality restaurant as well.

Yes the only reason that you have to prepay your tips is that with select dining you will or at least probably may have a different waiter every night.
I prepaid my tips on my cruise in October on Solstice and at that time it was advantagous to do so due to the exchange rate.
Contract to opinion that if you pre pay there is nothing for the wait staff or cabin steward to work for. I found absolutely the opposite in that I had the best cabin Steward ever. He brought my breakfast each morning rather than the Pantry Maid and told me anything that I wanted just to pick up the phone to him.
I wonder if it was just luck or whether he was working so hard for possible extra tip or for a good recommendation from me or whether it was just pot luck.
I am booked on the Equinox in April and I intend to pre pay tips again as I have booked set dining but if I should want to eat Select some nights on the days that we are in Port. I normally have late dining but taking a friend along and late is too late for her.
I don't think I will encounter a problem with this.

Sue

I read over at cruisecritic (I think) that you can still get select dining once on board, if you tell the service desk that you wish to prepay the gratuities; but only if you do so within the first day.

I don't know if that's true as I've never been on Celebrity. Would be nice if someone could confirm this.