Lets see the racket spec of V70 first and make a comparison with the other choice of rackets that you've listed.
V70 = Medium flex / Head heavy balance
AT900 P = Extra stiff flex / Head heavy balance
Arcs 11 = Stiff flex / Even balance
V80 = Stiff flex / Head heavy balance
You didn't mention how did V70 performed while you've been using it. If V70 has been giving you excellent outcome in all your hits then buying the same one will be a more logical approach. Unless if you have some performance issue with V70 then changing a new racket to match perfectly with your style of play will be a suitable move assuming that your technique is correct. Otherwise if it's just the urge to wanting a new toy inside your bag then you must decide wisely or it's just will be a waste of your money since Yonex is an expensive racket once bought.
You're currently using a V70 and shifting to a stiffer or more stiffer racket (V80/At900P) will only give you desirable outcome if your swing speed match those racket physical requirement. Unless you have the swing strength and speed to use such stiffness then upgrading to this racket might give desirable results in all your hits. If not then unlikely it will give you satisfactory results. Since V70 is a head heavy racket, the head weight of V80 and At900 P should not be an issue for you since this is the type of head weight that you need to use for your needs as an offensive type of player.
Arc 11 has an even balance head weight as to compare to V70 but has a stiffer shaft. If you're going for explosiveness in your offensive department, this will not be a right choice. Arcs 11 is more a control type of racket for an all rounder type of player.
Just so you know, I was probably at my prime with my V70. My shots were consistent, powerful, and controllable (for the most part). Since I'm relatively weaker with my wrist and arm compared to other advanced - professional players, I kinda of did rely on the slight flex.
I'm currently using my doubles racket (Nanoray 80) for singles just so I'll have an easier team adjusting to the flex.
Thanks so much for all of the technical info and your input!