Is there any downside to doing a larger-than-normal overhang on a kitchen island?

It's big, roughly 11.5' long, but the cabinets themselves are only 24" deep. I had always planned on doing an 18" overhang, but felt like the island was too long and skinny... We added a pony wall along the back, giving it another 5" or so of depth. If I stick with my original plan, the island top will be roughly 11.5' by 4'.

Recommended overhang for counter height seating is 15". With quartz countertops, I believe (?) I can do that without additional support. (Does it change it if the island is so long?)

With the pony wall, we obviously can easily add additional supports if we do 18". But, is it worth it, both expense-wise and hassle, for just 3"? Does 15" ever feel cramped?

If we do an 18" overhang, we still have 6 feet in the aisle behind, so space isn't an issue. It's more about visual (island looking proportional and not too long/skinny) and convenience.