Joe, I owned the REI UL 45 (similar to the 60), so I will give you my opinion.
The 'sack' portion of the bag is ideal! It has just what I wanted, a big lid, two big side pockets, and a brilliant "Internal Compression System" which cinches the contents of the pack uniformly and neatly along the entire length of the pack without any external compression straps. It also used light (not SUL) material, and comes with REIs lifetime return policy!
Unfortunately, I made use of that return policy because the suspension system design is just as bad, as the sack design is good.
1. The "Torso Length Control" where the harness adjusts along the center stay, is held on with velcro, which tore loose a little (separated hook from tooth) each time I picked up a heavy pack. Why such easy torso adjustment? How often does your Torso length change? Better to use a semi-permanent adjustment system like GraniteGear does.
2. The "Active Motion Suspension" (AMS) seemed like a good idea, but I discovered that with a normal pack, I make small adjustments to the 'ride' of the pack by shifting my hips or giving a little tug to one shoulder strap, thus shifting the pack weight back to the center of my back. With AMS my hip-shift, or strap tug was useless, it just shortened the opposite side's strap, adding strap tension inequality to the problem of the pack being off center. I thought about sewing the strap center in an unmovable position, but for the next point..
3. The shoulder straps were thin, narrow, and very uncomfortable. They use single density foam which is much too slight for the requirement. This constantly bothered me, and the pack was therefore uncomfortable. Every step I was thinking 'strap'.. 'strap'..
4. One good thing, the included waist belt pouch was a great feature; I miss that.(but GG sells one)
So, I went with the Granite Gear (GG) Nimbus Ozone with an optional lid. If I had to do it again I would get the GG Vapor Trail with the optional lid. The pack is only 2 lbs.
Bottom line IMO; REI UL packs have a bad suspension. Maybe you will like all the features #1-4 I mentioned, and just love the pack? As they say here, your milage may vary YMMV.
But, in my opinion, if you only buy one UL pack, get the Vapor Trail; those packs are extremely comfortable, and light. For me, I just don't want a 2 oz cuben fiber pack; the pack is something I will be wearing all day; Ill suffer the 2 lbs of weight (for the Vapor Trail for example), for a pack so comfortable I literally forget I'm wearing it; and just enjoy my day.
Incidently, after I bought the GG, I loaded both packs and tried them on; the REI felt like a board on my back compared to the conformal foam GG uses!
By the way, I did keep the REI UL Flash; it is a great UL pack for day hikes.
Here are some commercial packs sorted by weight; might help in your decision.