You cannot go wrong with either option. Cannot wait to see what you decide.
Personally, I am would do the 3 stone. 4+tcw is going to be ultra blingy. If it is turns out to be too much, the two 1 ct side stones can always be re-purposed to earrings.
I’d have to go with the 3 stone, personally! In theory, getting the 2.7 now and switching to a 3 stone in the future sounds like a great idea but I seem to move at a snail’s pace with projects so I’d probably be 80 by the time the 2.7 to 3 stone happens. Plus I think deep down 3 stones are my favorite style anyway.
They're both gorgeous and depends on what you want. I personally love how the solitaire POPS on your finger but 3-stones always look great for the wall of bling. That said, I would vote solitaire!