I havnt held or shot a gen 4 glock with the interchangable backstraps. Nor do I plan on buying one. Fortunatly for me the glocks fit my hands as is. I had a gen 3 G36, n shot it well. The compact and subcompacts fit my hands the best and thats what I plan to stick with. As far as too late, I dont know myself. But I feel that those who like glocks will try the gen 4 to see if it would fit their hands better, and those who dont woulda never givin a glock a chance in the first place. Im not even sure I would care for a slimline glock.