I guess the difference is that the SLICE designation is PPLNS but the N shares is a template determined algorithm? Either way PPLNS seems the most fair it's just how to determine the "N" of shares that seems to differentiate these versions. Only care that miners: Create their own templates Broadcast their valid blocks not the pool Have access to transparent share accounting system The pool's obligation is: Keep share accounting Rebroadcasting valid blocks found by workers Have several template selections If those criterion are followed, that could be ANY pool.