Suck back in a-frame? Raise last two stages up and let gravity help? I do both depending on my situation. Just curious on 

Never, I mean never, suck balls. A 8" x 8" square sponge is much better. If you can, always raise the last two stages to let gravity help.The best bet is to use a go devil.

I never use any thing other than an orange medium ball. They last up to 6 months and the boom is always clean, a sponge lasts maybe a month. If you suck the ball back in an a frame position when the ball goes over the top slow it down. I have used the sponges and will never go back. i fought with operators cutting sponges and dirty booms plugging on the prime. No more  

i have kept a sponge for 8 months, washing out 3 times a day. Just like anything else, it's all how you take care of it. I've also seen round balls roll over concrete and leave buildup, especially in the turret.

I have seen soft balls leave buildup behind but never medium to hard balls. Balls wash out way easier and faster than square sponges. each to their own......

I have been suckin a medium ball back for my 3 years of Pumping. Never once have had a stich of buildup in my boom, or had a problem priming out. My current ball is well over a year old and good as new, on average 2 washout's a day. I suck back idled all the way down and volume all the way down. Ball is throughly cleaned during every washout. A-frame or raised up depends on the situation, but as long as she's brought back slow there shouldn't be an issue. My boom is 5in all the way through. When I run our 47 which drops to 4.4 at the 4th stage...I do things a bit different