No, a share is a share. You get rewarded proportional to hashrate regardless of hashrate. Yes, even the lowest hashrate Bitaxe will work fine.

A fun thing you can do with DATUM, BTW, is to intentionally set the minimum difficulty *higher*. It will take you longer to actually find a share, but then that share will be worth more. In that way, you can actually emulate a lottery with whatever odds you want: "lottery mining" with a full block rewards isn't the only option anymore.