I use button gauges on my deco bottles but not on primary gas bottles where gas management requires having a more accurate reading. A button gauge just won't give you a close enough estimate of the amount of gas you have in your cylinders. As for keeping the SPGs from sticking out like curb feelers, if you have diaphragm 1st stages you can orient the cylinders so the 1st stage is facing up in your armpits. This will put the SPG right in front of your shoulder rather than sticking out in front of you. If you look at most 1st stages you'll notice the HP ports have a slight angle to them pointing them away from the DIN/yoke side. This is what makes them stick out so much when the 1st stage is facing away from you on the cylinder.
Probably one important piece of information to know is how people are orienting their valves. If the valve face is away from you,that will stick the first stage out further,and the spg will not be close to you. This is acceptable for open water/non-tech sidemounters where streamlining and danglies aren't critical. I prefer to have the valve facing toward me,and that brings my spgs very tight against my body since the first stages face me. I prefer Sherwoods for the first stage,and mate them up with the another make of seconds. Sherwoods have fallen out of favor in the tech world,but at one time they were the regulator of choice for cave sidemounters because of the dry bleed system and durability. I like the orientation of the first stage which allows my spgs to fit tight against my chest in the midsternum area.