I have one also. Can confirm the blowback. Spits in your face quite a bit. Tough can and the mounting system can’t be beat. Though, there is nothing so special about it that would make you select it over a Wolf(man) or Omega 9k. I prefer both of those cans greatly over the Surefire. I have a Phoenix on transfer as well and have shot it only at the indoor range. That is a great choice also. I don’t regret buying the Surefire because I like cans and I like shooting and comparing them, but couldn’t recommend it to anyone as a first or second sub gun can.
I didn’t notice any POI shift on mine, tho I will double check next time I shoot it. I have shot it on both my MP5 and MP5k.
Of all my sub gun cans, the Wolf(man) is my standout favorite by a wide margin.