Boaphiles sag and bow over time.
Visions sag and bow over time.
....and APs do too. I have several of them and have had to modify them with aluminum braces to reverse the sagging. The sagging was getting really bad on my 6' cages - up to 1/2".
I don't keep bloods, but I do keep some heavy colubrids in them (9 lbs). The weight of the snake doesn't change whether the bow or not - I've had AP cages with much lighter animals bow just as bad.