Well you have to remember that this reviewer was comparing the mid range and upper frequencies when he stated that the 450's matched the 800 series speakers. I wish I could find that link to the review (it was posted in the lengthy AVS DefTech thread, but I'm not going through over 400 pages to find it.) But I recall reading the review and how if you took out the the bass capabilities of the B&W 801 speaker that the 450 matched it with the mid range and tweeter sound. I have never heard a DT Prosub 60. I have only tested the Trinity, Reference, Supercube 1,2,3 and although I wasnt that thrilled with the supercubes (as compared to internet subs) the reference and Trinity were very good (the Trinity was jaw dropping, but for the money I'd get the SVS PB13 Ultra and save some coin.) I don't like comparing the B&W 801's with the 450's because I have never heard both of them side by side in fact I have never heard them together in the same store, but i have heard both and both are fantastic for what they were designed to do.
Personally i would want the 801D's but if I bought those, I would need to sell them for reconstructive surgery to have the "boys" put back on after my GF would find out how much I spent on speakers and would promptly "cut em off with a dull butter knife" (yes that's an exact qoute-sigh)
I think for 300.00/pair you would be hard pressed to find a speaker with that fantastic of a sound quality and constructive build. Not even the Gems which cost slightly more even comes close.
But I would hurry and order em, I have no idea how long 6th ave.com will be offering this great deal. For those who live within driving distance of 6th ave. How they can't be driving there and clearing them out is beyond me. I mean sheesh 248.00