Quote Originally Posted by shokhead
98% of LFE is 25HZ and up so why get a sub that goes lower? No center and you can get the dialogue from the mains. No surrounds and thats all lost.
Your argument about the LFE isn't quite a proper analogy in this case. This really all depends on your priorities. I could use your LFE comments to strengthen my point: If you don't have the budget to do it all, do what you can. In this case, if all you can afford is 25Hz LFE, ie: get 98% of the LFE and don't sweat the small stuff. Prioritize where most of the important information is. Actually, many serious hi-end 2-channel audio systems don't bother much below 27 Hz...there's almost no musical information there.

Not all "surround" info is lost by having no rear speakers. The signals are instead routed to the front channels anway, and much of the ambience occurs from natural reflections in your room. Throw in a decent Virtual DSP and you can get by.
The undisputable fact remains, once you move outside the sweet spot in any room, often just a few inches, the phantom image disappears, and instead your brain processes the louder information - this is known as the Haas (or Precedence) effect. So while you don't lose the surround info, you DO lose the center image and it's all skewed to whichever speaker you're closer too...nothing worse than watching someone in the middle of the room but hearing them in the corner, especially since dialogue is used much more than surround channel info.
... I'm not suggesting not to have rear surrounds, but rather if compromise must be made, I'd sooner have the most important, and most used parts of the soundtrack at their finest until such a time as adding surround speakers is feasible (unless you are absolutely sure you can always be in the perfect sweet spot and could care less about other people's listening experience, in which case I would agree with your approach). YMMV