Yup, $750 is different.
I'm sure you'll be happy with your choice.
FYI . . . Sale with code ended 11 march. Newegg kicked sale on again yesterday with no coupon code. On sale at $299 with free shipping . . . as long as they last. . . They might be making more still with old stock.
I have a pair of Heresy 1.5s. You say, there is no such thing. True, but 1.5 is the unofficial nomenclature for Heresyes built after the early modern Heresy was discontinued and they started building Heresy IIs. Some late year 1984s and came stock with some parts from Heresy Is and some parts with Heresy IIs . . . Until they ran out of old Heresy I parts from the stock bins all together.
These late build 1984 Heresys with some 1985 parts are unofficially referred to as Heresy 1.5.
So, it is possible there upon discontinuing no,new Klipsch RW12d parts were made, but as long as parts were in stock, Klipsch would continue to build RW12Ds from parts no longer made, but still in stock. So, say a year from now, when there are no more NIB RW12Ds, you may be able to call Klipsch to get a part replaced under warranty, or buy parts 10 years from now, saw a frill, if they still have it in stock and if that NOS of that part is still in hand with Klipsch.
So, for the RW-12D no new parts are manufactured after are secured, but subs would continue to be built long after discontinuation if there are enough parts on hand to continue making them . . . To move them, they are of course discount, and made, until one of the parts is emptied out of stock . . . Then, magically no new discontinued RW-12ds enter the pipeline.
Are the RW12-D's discontinued? Yes. Are new parts being made? Some third,party parts, sure. Can a discontinued sub still be assembled new? Yes, as long as all of the on hand/supplied parts are available. When one unique part of the RW-12d becomes unavailable, (say, the cabinet), then when the leftover parts prove not enough to assemble one sub all of the remaining parts on hand become NOS part for sale, parts to be sold individually until they are gone.
IMO, Let your eq (room balancing) software built into your AVR decide, if your avr eqs two subs simultaneously like some do.
Otherwise,, I recommend you set both subs the same to start . . . Listen for a while that way (hours or days) for your ears to experience and establish a baseline for your real world experience; then start tweaking one of the subs . . To see what you like best. Tweak with them both . . . They are your subs . . . Do it your way. :-)
Or, get an SPL meter, and REW software on your laptop/computer and let the measuring and stats tell you what you are supposed to like, if measurable statistical results are more in your comfort zone.