Since I've bugged a ton of people regarding this I figured I'd share some feedback now that I have 2 good rides under my belt.

My former set up standard chorus 53-39 10 speed cranks and 11-23 cassette in the back. I'm a small guy at 5'6 about 147 lbs. and a decent climber (for a recreational rider). My problem was the long steep climbs (6% +). I could do them fairly well but I'd tire out way to quickly staying on the 39-23 combo and mashing at about 50-60 rpm.

Friday I had the 50-34 FSA mega exo SLK compacts put on my bike (kept the 11-23 in the back) and here's what I noticed as I did the same ride I did the prior week yesterday:
1) I have about 2 clicks more then last time
2) Probably psychological but it did feel somewaht lighter but not necessarily stiffer than my old chorus
3) If ever I probably went SLIGHTLY faster uphill
4) The key difference I was definitely feeling better rested at the end of the ride to the point where I'm a bit disappointed in myself today as I feel I may not have pushed myself hard enough. My heart rate would disagree but my legs seem a bit to bouncy after too hard rides.

Downside
1) I need to get used to the gears (as I'm not used to having the extra clicks) and timing when to use the harder gearing
2) Possibly on a downhill a larger/stronger rider you spin out on the 50 11 but that wasn't the case for me (but I thought I'd bring that up)
3) I'm still trying to work with being at the verge of cross chains

So in my humble opinion this is an awesome upgrade. Perfect for someone like me who feels that they have maximized their current gearing set up and would like to face even harder climbs with spinning option (but not too much). It will not make you faster per se but used properly it will keep you fresh for the push at the end.