Peach mains don't really have any business boost-grabbing, at least I've never seen any point in it. And, well, as far as I can tell, nobody else uses them either (:
If not for losing frames to jumpsquat jc-grab and standing grab actually have the same startup
I think the main question that should be asked is: Would you rather have slightly more range on the grab, or is the lessened vulnerability more valuable to you in the given situation?
I'd say that when chain grabbing you usually can make good use of the range boost (and sometimes have to), and won't get punished even if you miss, and you're not going to get a bandaid techchase even if you do JC grabs either.
Whiffing grabs in neutral is going to be punished in either case, might as well go for maximum range again.
I'd only consider JC grabs in situations where they are on the defensive, and might be too flustered to react correctly to a missed grab.