Just my experience talking, but unless you circulate a LOT, I don't see a darn bit of difference in the end result. We don't recirculate any of our wort.
You need a false bottom or a similar solution definitely. With all-grain, it's important to never disturb the grain bed. It acts as a natural filter and the water percolating through it gently rinses the grain. Think of sparging like making coffe, where the grain is coffee (and there's a lot of it). Hot water in the top, coffee out the bottom.
So you add grain and hot water to your mash tun, let it sit the appropriate amount of time, and then start adding hot water to the top and draining out the bottom, gently and slowly. So you need something at the bottom to keep grains out of your wort. That's the false bottom...like a coffee filter.
Personally, I have had miserable luck with false bottoms, so I always build a manifold out of copper or CPVC pipe and use that. I make a loop of tubing, drill holes in the bottom and attach that to my outflow valve on my mash tun. Works like a champ.