I'd get the rest of your gear reduced down to lightweight before replacing the pack. Heavier gear in a lightweight pack usually doesn't work too well. Once you get your other gear items reduced in weight/bulk, then look for a lighter pack.

It's the same principle as for new pack buyers--get your pack last! I did the same for lightening my load--bought a lighter pack (just under 2 lbs) when I had my base weight (everything except food, water, fuel), including the contemplated 2 lbs. pack weight) down to about 15 lbs. I had the gear, plus a mockup in bulk/weight of a week's food, ready to go when the new pack arrived.

Have you discovered the useful articles and gear lists on the home page of this site, left hand column? There is also useful info in the "sticky" from phat at the top of the Beginners section of this forum.