I believe what Thermarest is claiming is that the reflective coating provides a 14% increase in warmth with no added weight, which is correct. The reason the RR Solar is heavier than the regular RR is because the RR solar thicker, not because the coating adds weight. The RR solar is actually a RR deluxe. They are both 0.75" thick, whereas the regular RR is 0.625" thick. Essentially, Thermarest has simply added a reflective coating to the RR Deluxe to boost R-value at no weight gain and given it a new name. Hopefully down the road they offer a solar version of the regular Ridgerest so we can get the 0.4 R-value increase on that mattress too, at no additional weight.
Even better would be if Thermarest offered a new RidgeRest Solar UL, which used the reflective coating idea to give you the same R-value as the regular Ridgerest but in a thinner, lighter package. I bet a 0.5" solar Ridgerest would have about the same R-value as the current 0.625 Ridgerest but it would be lighter. By offering the 0.5" RidgeRest Solar UL you could get similar warmth and comfort for a few ounces less.