I'm about 1" taller and 4 years older than you, and about the same weight, if that matters. I have a standard double (53/39 with 11-25 (I think? Maybe 11-26?) on the back) and it works fine for me. We don't have mountains around here, but we do have some big hills (around 15% is the max grade that I ride somewhat regularly, but I can find 20%+ if I want to). Mostly rolling stuff, but I can make up routes that contain 3-5 big hills over 40 or 50 miles if I want. The steepest stuff is borderline for my ability, and a challenge for me, but otherwise I don't feel a need for lower gearing. I stand up and crank when I need to, and I like that it makes me stronger.
For comparison, I do find that on one particular hill where I need to stand up on my road bike, I can remain seated on my touring bike with a triple. But I like the variety of occasionally standing - you may or may not.
It's a personal choice, and if you are used to using the lower gears and you miss them, then get what you want. Just don't think that you can't ride a standard double if you choose to. You mention that the hills are noticeably harder - are they way too hard now? Or just not as easy? Sucking the life out of you? That should factor in there.
The Warrior Princess: 2008 Jamis Xenith Pro / Bontrager Affinity 1 (men's)
2006 Trek Fuel EX 9 / Bontrager Race Luxe
2007 Trek 520 / Serfas Terazzo
Amelia Pond (She travels long distances, has great adventures, and she's a redhead): 2007 Trek Pilot 5.0 / Bontrager Affinity 2 (men's)