I used to use 110 (or 70 - same thing) degree swivels on my primary 2nd stages. I recently changed them all for 360 degree swivels from Cave Adventurers.
Cave Adventurers - Swivel - Marianna, Florida USA - Never Undersold!
I definitely like the CA swivel better than the fixed angle swivel.
I do not currently have a swivel on my 1st stage, but I am planning to order one from Piranha and add it to my 1st stage.
First Stage LP 360 Swivel
The hose for the primary 2nd stage coming straight out the side of the 1st stage is not really a problem. But, it does tend to make that hose want to float out to my side, instead of staying neatly tucked in against my side. Sometimes, depending on what I'm doing with my right arm, that hose can end up outside my elbow and I have to reach my elbow around and tuck it back in. And that is even with me having a MiFlex hose, which is more bendy. If I had a rubber hose (which I will change to when the current hose needs to be replaced), I think it would have even more tendency to float out to my side.
The downside to adding the swivels is that they add extra O-rings to your regulator setup. That means more potential points of failure. It's a tradeoff and you have to decide for yourself if it's worth it to you.