Just reading through this thread. I know the consensus is that a lower mash PH with a lower attenuating yeast should be sweeter than a higher mash PH with a higher attenuating yeast.
The question I have is using the same lower attenuating yeast (say Wyeast London III 1318), what is going to create a sweeter finish...a higher mash temp or lower mash temp? Conventional wisdom is that the higher mash temp would create the sweeter finish. However, I'm wondering if the higher mash PH creates more body but actually a drier perception?
I guess I've arrived to this thread late!
I, for one, will answer your question by not answering your question.
I think we all tend to forget that temperature is not the only variable. If you vary also the mash TIME (e.g., not every beer has to be mashed for exactly 60 minutes), then you may get the result you wish by mashing for, say, 30 minutes instead of 60 or 90 minutes or longer.
If you want "sweeter" or "more body", I do think mashing for just 30 minutes, or maybe even just 20 or 25 minutes, might get you the result you seek.
On the other end of the spectrum, it's been proven by many that if you want a "drier" beer, mashing for 90 minutes, or 120 minutes, or (gasp!) overnight will get you a very dry beer indeed. All using the same old yeast as you would normally use after mashing for just 60 minutes.
I say these terms like "sweeter" in quotations because it does, in fact, mean different things to different people, regardless of the previous technical discussions. We are all human; however, we cannot all be scientists who give a crap about the "proper" terminology.
Cheers and hope this helps.