That is an interesting idea! One of the reasons I stopped spunding was all the extra yeast in the bottom of the keg and for my smaller 2.5 gal batches it was taking me too many pints to my liking before I had clear beer. I've thought about cutting my dip tube even more than the half inch I have now but that would leave behind too much beer.
I use a little 3-gallon Brew Demon conical fermentor for my small batches - works great! And I picked it up on clearance at our LHBS.