I agree, it's really up to you. If you are happy with your phone the way it is, just keep on keepin' on.
If you want to experiment with ROMs it looks like the SG Ace has a LOT of
support and ROMs in it's
Root subforum.
The reason I rooted my Droid X after a few months of ownership was I wanted to use a screen cap program (ShootMe) which required it. It was a few months later till I tried and used a few ROMs but I seem to still come back to stock with root (where I am now).
Just remember: Rooting voids your warranty and probably any extended warranty you might pay for. Also there is a chance you can brick your phone (unusable), but the people here can walk you thru getting it back, 95% of the time or better.
If you do decide to root and ROM always read the instructions twice before starting. Most of the time the people writing the instructions, write them as seasoned ROMers, and beginners can get lost. But feel free to ask questions in your phones forums and root sub forum. That's what they are there for.
One more thing, if you do root, and want to change ROMs, backup your current ROM (stock) with Clockwork Mod. If you don't like what you installed, you can always go back to exactly where you were. (See, seasoned ROMers forget to talk about this stuff).