The advantage of straight stocks is that theoretically they allow the hand to slip down to a more comfortable position for the rear trigger. I have double trigger guns in both configurations, but I find the ease in gun mounting with the pistol grip stock outweighs any theoretical advantage of the straight stock. I even have difficulty with the rounded pistol grip on my Merkel 201E, as compared to the more pronounced one on my Perazzis. However, optically it's hard to deny that the straight stocked guns look better.

IMHO it boils down to a matter of taste.