I believe I'm the original poster who suggested the 12HO on the PE board.
Anyway, as I said over there, the 12HO was all about potential. Over here, you've added a budget constraint. With $250, looking at $120ish drivers limits you to plate amps in the 240-250 watt range. At that power input, the 10HF and 12HO are pretty much equal. The 12HO has the potential for as much as 6db more output in the 20-30hz range if you give it enough power...like 1000 watts, which is not going to fit your budget.
Also, a thought ocurred to me. On PE, you say the 2 ft^3 limit is internal volume. How did you arrive at that figure? Is that net or gross internal...the driver, port, amp, bracing aren't calculated as part of the WinISD models. Constructiong techniques can yield wildly different external footprints for a given internal volume. See GR-Research's plans for their 2.4 ft^3 internal PR
design...it's external volume is roughly 3.5 ft^3. You could knock that external down some by cutting back on the bracing and using a single thickness baffle...more tradeoffs since cabinet vibrations *may* start to color the sound at higher output levels. Looks like quite the deal though, at $129 for driver and matching PR
For a $250 budget, the 10HF and 12HO with a 240-250 watt amp are probably a coin toss after you place them in a room. They're also the best options I'm aware of that are close to your size requirements and in your budget.
Do you have an SPL meter? What volume levels do you listen at? We may be trying to get you more output than you need. Something like the DVC12 or 12HF in a 2 ft^3 sealed box will probably get you a smaller footprint and still give you decent low end extension...still 20hz usable output, but the smaller footprint will give up quite a bit of overall output.
You need to decide what your hard requirements are and where you can compromise. There are tons of options out there.
For instance, money no object for a small design...I'd probably choose the Titanic 10" in 2 ft^3 tuned to 20hz. Yields an f3 of 19hz. Not quite the maxSPL capability of the 12HF, but it goes lower and has a flatter overall response. Match it with the OAudio 500 watt amp for 108db @ 20hz. Of course, tuning a high excursion woofer that low in that small of a box is tough...a 3" port may not breathe enough so your budget goes up even more to add a suitable PR
or two, unless your design aesthetic allows external ports. Should be competitive with the SVS PB10, but the PB10 would probably be cheaper. :-)
FWIW, SVS only uses a 3" Precision Port in the PB10 and it has more excursion than any of the drivers mentioned here, but I don't think anyone complains about port noise with it...even though the rule of thumb says even the 12HO is under ported with only 240 watts input below 30hz. The 10HF and Titanic are pushing the recommended speed limit at 240 watts...the Titanic goes off the charts with 500 watts.
Isn't this fun? Good luck. :-)