Many will tell you that single leg is fine, but others will point out that L/R leg output isn't symmetrical for everybody all of the time. You really have to decide for yourself if you're okay with working with half of the story and guessing the rest. Honestly, I don't feel like a potential discrepancy between single (doubled) and dual would make a practical difference for me, but I'm just the kind of person that would rather know for sure.

Anywho, that in mind, if I were to go with a single leg solution, it would be one that's upgradeable to dual without spending too much more than going dual off the bat. At this point, Stages, 4iiii, Pioneer all have single-to-dual upgrade paths.

What I ended up doing, though - Powertap C1 chainrings. As of Mar 1st, Powertap/Saris is only selling them direct, but they bumped the price from $699 down to $349. This is a total power solution (with estimated L/R output, should you want that) for a very reasonable price, as long as your crankset is compatible (5-arm, 110 BCD without hidden bolts). My crankset wasn't compatible, but I tracked down an older Shimano crankset for less than $100 to pair with the Powertap. Do I like it? I don't know, I haven't received it yet - should be here tomorrow, I think.