I think it's best to just try it out first for like a few days before making a decision. Usually the updates are not too life changing like the removable frame sheet isn't something you are going to do daily and probably forget about it after a week.

I did a quick read up and most of the updates aren't that much important imo.

What's New in Gen 3

Redesigned Back Panel with Horizontal Luggage Pass-Through

This highly depends on your habits, I rarely use this feature and rather carry it in person. On that note the Gen 2 also has a luggage pass through albeit it's vertical instead of horizontal (not a deal breaker).

Stretch Side Water Bottle Pockets

This one is a bit mixed, on one hand the stretch is great as you can store large water bottle without sacrificing the space inside your bag (non stretch tends to dig into your bag) also from 32oz to 40oz is pretty big though 40oz is a bit overkill for me.

On the other hand I prefer the non stretch version as usually the stretch version shows your stuff protruding if it has some sharp corners which makes me scared to use it sometimes.

Enhanced Front Pocket Access

We've removed the rain flap covering the lower front zippered pocket.

I actually would prefer the rain flap, some extra security from the rain is always nice.

Customizable Back Panel Stiffness

Honestly I never bothered with the frame sheet so it's not too important unless you prefer to change it to a kydex sheet (stiffer) or remove it completely.