it did help a lot, especially on seated climbs on the trails
went from a very short stem about 50mm to about 90
wiggle has some Deda stems on sale now at $22US

your riding posture looks fairly good, you may want to consider a 120mm stem instead of the adjustable, since your seat is already all the way back

also the saddle slid backwards will rotate your hips forward activating your front leg muscles more, but to counter this change in position, you could be pulling back on your bars and putting tension on your lower back

on long climbs, I usually slide back on the saddle, and hold on to the flats of the bars since i don't need brakes during climbing, if I had to get to the hoods, it would likely stretch me out too much