Most panels have around 14% efficiency, so yours at 19.9% are 20/14=1.4 times smaller per same wattage. This is important if you roof area is not big enough for solar wattage that you want. If roof is big enough, then this is not important.
Efficiency drops by 1% a year for rigid panels. In flexible panels like yours I would expect it to drop faster, because there is no protective glass layer and clear plastic degrades sooner. So, in a few years the efficiency of this particular panel could match the efficiency of rigid panels, and then it will become lower. But again, if you have enough total wattage after this aging degradation, this doesn't matter. This has been said on this forum many times already: if you can get more solar wattage, - do it.
