[Hokerer]

I do have the option of picking up the 78qt Coleman extreme-question is this:  Is this too large a size if I wanted to so a 5 gallon batch?

All of my 5-gallon batches have had plenty of extra room in my 36-quart Coleman Xtreme.

When or if you start messin around with 25 lbs of grain say for a barleywine or other high gravity bill,
the 36 quart will be a disappointment....IMO

When I start messin around with 25 lbs of grain just shoot me in the head   The biggest I've done (and probably the biggest I'll do) was a 1.075 IPA and the 13 lbs of grain for it plus water fit just fine in the 36'er.  Most of what I do is in the .40s and .50s so the 36 quart is actually better for those as there's still some decent grain bed depth that wouldn't be there in one of those mondo size coolers.  I guess it all really depends on what kinds of brew you do.

[1vertical]

Well, I have the rectangular BLUE coleman extreme. I like the divot in the bottom
for the drain. It helps get the last nth of wert out. It allows me to make Either
5 or 10 gallon batches.  AND I could always use it for the high gravity 25# of grain
stuff as well.  It just allows a lot of flexibility for multiple varieties.  I looked at the
circular styles as well, and the 10 gallon cylindrical gott orange was kind of spendy
compared to the blue coleman extreme.  I believe without doing the math,
volumetrics are greater in the blue.  As for the corners and dough in,
I use a large wire whip and have absolutely no problems with dough balls.

[denny]

As for the corners and dough in, I use a large wire whip and have absolutely no problems with dough balls.

I use a large metal spoon and likewise no doughballs.

[bluesman]

I currently use a rectangular cooler and it's easier to dough-in with my mash paddle as I can break up the dough balls against the flat wall.