Hmm, I know "nothing new on race day" but that said, if you can get just one or two sessions in the new suit and feel good, I'd probably go with the new one if it is of similar style to your current one.

My thinking is it will be *your* suit, it's new and in great condition, and you may just feel faster and/or more comfortable in it...

If you don't think you can get any practice time with it, probably better to go with what you know.

Either way, pick one and move on to other decisions - I'm sure you will find more interesting things to have your mind wonder about!