I drove an early prototype GT without the Sub, and several months later I drove one with the Sub. It is not an overstatement to say I was blown away (in a bad way) at how much I hated the Sub. The blocked view of the engine (something I LOVED about driving the early prototype) was my first point of contention. But as I drove the car around over the course of two days I grew to hate the claustrophobic feel it gave the cabin and the way it hampered my interaction with passengers.
When I ordered mine I had every option checked except that one and my dealer actually called me up, "Did you just forget to check the audio upgrade option?" I responded quite emphatically, "NO! No McIntosh! No McIntosh!"
It's truly ironic, because I grew up with audiophile brothers and became one myself, and I love classic American audio components (Harman/Kardon, JBL, DCM, and McIntosh). And yes, I'm a big fan of tubes, too. I thought it was cool when Subaru started putting McIntosh audio head units in their cars, particularly because they had the classic McIntosh style to them with the big metal knobs and such. If Ford hadn't used that Sub design I would have been thrilled with the head unit, but I'd rather have the base unit than that giant black hole in my car.
In a perfect world I'd have gotten the McIntosh head unit with no Sub, but I hear that removing the Sub requires a big re-work of the wiring just to keep the head unit playing (not to mention the cost of the OEM panel between the seats). What a nightmare. Glad I avoided the whole mess. I plan on putting in an aftermarket head unit soon (yes, I'll be putting the factory stereo in padded box for posterity). I demand MP3 capability from my cars these days, and if I can make my 1970 GTX and 1973 Saab Sonett play them, I expect my 2005 Ford to do it, too.