Definitely don’t want her pissed but may have to take one for the team and get the vtf3s, just because I wouldn’t wanna have to upgrade in a few years because I wasn’t happy with the vtf2s
Here's my thought on this:
We are "audioholics", we're generally always going to encourage you to go for the best!
However, unless I'm misremembering, you said you were not a bass head, and 4 Hsu (or equal) ported 12" subs (or 4 sealed 15" subs, which is what I have) is a lot of low frequency energy to pump into any residential room. Of course, there is more/better to be had from a no-compromise perspective, but the question of "how much is enough" is one that ultimately only you can answer.
I can tell you that for me, four 15" sealed subs is more than I need! I never work them hard. I've forgotten how big a volume you are filling, but the immediate room my system is in is 4230 cu.ft.. If I add permanently open spaces to that area it gets just over 9000 cu.ft.
I do like the thrill of my subs causing a visceral sensation when a dinosaur stomps and my adrenaline kicks in, and 4 sealed 15" subs delivers that for me! I'm sure if I had 4 ported 15" VTF-3 to A-B compare, the VTF-3's would impress, but I do not feel deprived in the least with what I have (otherwise I would have changed it by now - no WAF concerns, but I do like my room more open, given the choice).
I have a Denon AVR which allows me to setup differently for different sources. So, I have my DVD input set to run the subs 4-5dB hot to get the "WHUMPF" I like.
I actually have my CD input set to -2dB! I think Audyssey did a good job of setting the level, but there are so many songs where the recording engineer recorded the bass hot (or maybe they did not use subs when mixing). For me, this totally destroys music (the attacks at higher frequencies seem to lose resolution - in other words it sounds sloppy instead of tight)! I am not one to adjust for every song that comes on, so I have found -2dB to be the best compromise of still having good bass on a well recorded songs, but not allowing the recordings of great music with heavy bass to totally suck!
(For my music system, I am looking at some options that have a subwoofer volume level on the remote for easy adjustments on the fly.)
OTOH, so much of this has to do with your room and how much room gain you get and how well Audyssey (assuming you are using it or another room correction feature) handles your specifics. Fortunately, the subs you have been considering all have good tuning options so hopefully you can get it good enough for Audyssey to be able to handle the rest (tune your subs as best you can
before Audyssey).
VTF-2:
To bring this review to a close, anyone looking for a subwoofer in the $600 point ($539 + $60 shipping for continental US) would do very well to consider the Hsu VTF-2 mk5. Its overall performance and feature set is one of the best, if not the best, that can be had at this price.
It achieves our Bassaholics “Large” room size recommendation in the ported modes (meaning it is suitable for rooms from 3,000^ft3 to 5,000^ft3),except the sealed mode, which nets the “Medium” room size recommendation (room sizes of 1,500^ft3 to 3,000^ft3). The VTF-2 mk5 is the least expensive sub to capture the “Large” room size recommendation, which is a nice new precedent for those looking for the most bang for their buck (more information can be learned about our
Bassaholic Room Size Rating.) The VTF-2 mk5 also carries a feature set that is uncommonly good for subwoofers in this price range as well. Along with the hardware, the buyer also gets Hsu’s well-regarded customer service, a 2-year warranty on the amp (upgradable to a 5-year warranty for an additional fee),a 7-year warranty on the driver, swift shipping, good packing, and a subwoofer with manageable size and weight that isn’t an eyesore and doesn’t need a two-man team to move around. I have to give the Hsu VTF-2 mk5 a strong recommend for what it brings to the table for the cost, and if I were shopping for a subwoofer at its price point, it would very likely be my first choice.
https://www.audioholics.com/subwoofer-reviews/hsu-vtf-2-mk5/conclusion
ULS-15:
Now let’s briefly go over some of the highlights of the ULS-15 mk2. Its sound quality is superb, and the high fidelity that was heard in the listening sessions were confirmed by the measurements. The ULS-15 mk2 is a very accurate subwoofer and demonstrated highly linear behavior across a slew of different measurements. The output is tremendous for a sealed subwoofer at this price point, and this sub qualifies for Audioholics’ Bassaholic ‘large’ room size rating (in other words it should be able to meet the target 115 dB peak in seating positions in a 3000 ft^3 to 5000 ft^3 room). The tremendous output can be gleaned from the burst tests and compression sweep measurements, but nothing is as convincing as sitting cross-legged on the floor with the ULS right behind you only a couple inches away, and then cranking a hard dubstep tune to reference level on the AVR. Do that and you will know what a punching bag feels like.
https://www.audioholics.com/subwoofer-reviews/hsu-uls-15-mk2/conclusion.
Good luck with your decision! The good thing is I don't think any of the gear you are considering would disappoint!