OK; I'm still conflicted! These two seem like a coin-flip.
Exped SynMat UL 7: R-3.1; 16.2 oz; two valves; packed size 9"x3.5"; no pump; $165
Exped DownMat Lite 5: R-4; 22.6 oz; one valve; packed size 9"x4.3"; pump included; $99
Reading various on-line descriptions, I can't tell whether there's a difference in construction of the air chambers (as, for example, with the SynMat Basic 7.5).
On the whole, I'm leaning toward the SynMat UL 7, but the R-value difference is nagging at me. I doubt I'll ever do serious winter camping, but it gets pretty cold in the Rockies at high elevation, even in the summer, and my BA bag is uninsulated on the bottom.