-I just want to address some points. Doa4 overall had lack luster stages compared to both Doa2 and Doa3. With that said, ninja hideout, the monkey temple, gamblers paradise (sans the cars), sea side market (top level only), and maybe the safari are up to par.
-Being 100% brutaly honest, having Vf characters in Doa does jack shit for Vf. The characters look better and are more fluid in Doa. The only thing these characters did, was solidify that Doa is a competitive fighter in the like of Vf, Tk, Sc...etc. Something Doa alone could not do...great marketing Team Ninja! Some may say that these Vf characters brought a level of deph and sophistication that was sorely missing from the series. This is absolutely incorrect. Those who are astute in the Doa series will tell you that these characters bring to Doa5 what was already heavily present in Doa3.1. So the need to use Vf's engine to better Doa is totally not necessary. Doa built a solid foundation with Doa2, and brought the series to the right direction with 3.1. If truth be told, Vf have been borrowing heavily from Doa since Vf4. So infact, Doa need less Vf and more polishing of its own engine!
-Addendum: In retrospect, the addition of the Vf Characters proved what the members on this side of the community have be advocating all along. That Team Ninja should have used Doa3.1 as the base, and built up from there. The Vf5 Characters play exactly like Doa3.1 characters(proving my point how Vf for the past two iterrations have been heavily influenced by doa), no joke or exaggeration. Imagine if TN used 3.1 as the base for Doa5.....Doa5 is not bad, but it would have been freaking perfect! With all the tweaks in Doa5, with 3.1 as the core.. Doa5 would have no doubt about it being competitive enough. There would be a plethora of strats that would take the series to new heights...surpassing our beloved 3.1. The fact that Ultimate is bringing back the classic stages that provided unsurpassed levels of environmental positioning, tactics, setups, baits interaction, character positioning, terrain awareness ect.