I own the IPS, and it's a great shield. But after seeing my friend's Vile Striker do more damage than my Dread Venom Striker (probably because his was almost level 10 and mine only had a few levels) I feel like building a BTS.
I've noticed that IPS and BTS have about the same amount of piercing defense, so essentially I'm trading a chunk of normal defense for a decent damage bonus. And I'm okay with working on BTS, because it won't outclass IPS due to the fact that not only does IPS have more defense (especially because I have a medium normal defense bonus on it), it has stun resistance which can prove to be quite useful against lumbers, trojans, and anything else that can inflict stun. And yes, normal defense UVs can stack on IPS, you just can't see it.
So yeah, other than the main debate I'd like to know how much damage is gained from a medium and maximum damage bonus. If nobody here has achieved a maximum damage bonus, just tell me your highest damage bonus so far and how much extra damage you deal with whatever weapon you use.
If DVS is the only sword you use, its not worth making BTS. Stick with the better shield instead.
Medium+maximum damage bonus doesn't give you anything. No offensive bonuses stack beyond 6 levels.