Not the Sportical but I have shot and handled an LR-308B. I think it's good for the money. I cannot find anything wrong with it, but I don't get the warm fuzzies of a really mil-spec weapon.
IMHO, things in favor of the DPMS:
-lowest entry price
-best selection and availability of magazines (various brands including DPMS, C Products, and the new Magpul 308 Pmags, as well as old production original AR-10 mags and whatever Knight's Armament is using for the SR-25)
-reputation for outstanding accuracy
-seems to have the most aftermarket options
Things going against the DPMS:
-it's a DPMS
-some corners were cut to get to the price point. The magazine release button that's borrowed from an AR-15 but as a result barely threads in to the post from the mag catch is the most glaring example.
-not all that close to anything that is actually mil-spec (neither is the RRA LAR-8, either)
-all the barrel options I know of are button rifled, unlined (comparable to RRA, but Armalite offers you either chrome lined or match stainless)
-short 3-year warranty that seems to become void if you change ANYTHING, even little accessory parts
When comparing the Rock River option, bear in mind that FN-FAL mags are not as cheap or easy to find as they used to be, with no 20rd mags currently in production that I know of (although DS Arms is supposed to start producing them sometime soon). In contrast the DPMS has multiple options (both brands and capacity) for current production mags at affordable prices, and the Armalite at least has a range of mag sizes in current production (no real choice of brand that I know of, however, and prices aren't cheap).