I've heard exactly the opposite about accuracy. What the shorter barrel costs you is muzzle velocity, but not too terribly much for the 14.5" vs the 16".
Shorter barrel means less droop and whip, which can theortetically enhance your accuracy. Lower velocity will lead to more drop and wind drift, so it's a tradeoff.
The other advantage to a longer, heavier barrel - besides velocity - is that more weight provides a steadier shooting platform for unsupported firing positions. From a bench, though, there should basically be no difference due to weight and length.