I have the Lumia 930 as well. Out of curiosity since you have both which do you prefer overall in terms of build and functionality?
Still on first impressions only, honeymoon phase lol,
I miss the pillowy feel of the 930 glass, I liked the 920 feel too. The 950xl is pretty flat.
On my 930, I tired of the metal frame and the buttons for me were getting annoying cause of unevenness in how depressed they were.
I am a fan of how both the 920 and 930 feel very solid with heft. The 950xl surprises me in weight and thinness and the poly is more comfortable in the hand compared with the metal band on the 930. But I would still say I like the 930 more for the size and overall feel, heft. This is compared to out of the box though and I fully expect to change out the back cover so this would change depending on what I picked. But that's a good thing about removable back I guess. Make it your liking.
Even with the size difference, I found no trouble transitioning to the new size.... being able to adjust the keyboard is helpful. I like the metal buttons of the 950xl, it feels solid and you can really tell they are there.
I don't feel a difference going from hardware buttons to on screen buttons.
I don't feel regret in getting it, I don't feel like it's the most amazing transition either but happy so far nonetheless. I'll make use of that extra screen real estate soon enough