I agree.
I used REW to determine that I can't locate bass until about 80hz. I have the HPF/LPF on my receiver set to 100hz because even then it's hard to localize. With a pure 100hz tone I can localize the bass to somewhere in the front stage. So far, I haven't been able to localize the subwoofers even with a 100hz tone. With real content I have never noticed from where the deep bass is coming. I've watched several movies with my subwoofers in place and my xo set to 100hz and I have not had an issue yet. Nor have any of my fellow movie watchers or music listeners.
My W15GTI MKII's are much better suited to play loud bass tones than my Phil 2's. The more work I can take away from the SB the better.
When I first got my sub this was pretty much the conclusion I came to, and set the high-pass filter for the sub at 80Hz. After I got the sub I acquired the OmniMic and began measuring and experimenting more, and I found that with mains that were flat to below 30Hz it was advantageous to run the mains full-range, and use equalization and placement of the sub to smooth, fill-in, and extend in-room bass response from the mains. Gene mentioned that he was using a similar strategy in his system. I can't speak to the Phil2, but with the 802D, which are flat in-room to just below 30Hz, it seems like a waste of two high-quality bass sources not to run them full-range.
I suspect for those people with multiple subs, like you and ADTG, it might be that the win from more than two bass sources is subtle, but running the mains full-range saved me from needing another monster sub in the room.
One big advantage of using subs is the ability to adjust the volume of the bass octaves relative to other octaves in a very precise way. Full-range passive speakers can't do that (at least not without reducing sensitivity to very low levels), and the ability to boost or cut bass precisely has led me to the conclusion that I'd never be with at least one sub again.
I'm not sure what I really think yet about the question of whether multiple subs make more modest mains equal to the most extended ones, as haraldo mentioned in the 802 versus 803/804 debate. My sense from experimenting that the most ambitious mains are always better for blending with a powerful sub. I suspect it is because you want the frequency responses of multiple sources to be as similar as possible, and perhaps a speaker that's rolling off below 50Hz or so won't work as well.