10'x for these test. As you can see from 1'st and 3'rd upload graph - basically in terms of upload bandwidth utilization there shoudn't be a difference. Slot focus is mostly for releasers - so that full chunks are spread as fast as can be, "evenly balanced" slots are for downloaders (larger number of clients in circulation - sort of minor credit shaping) - or for scenarios were slot focus doesn't function as it should. Most mods are offering only one method, I prefer my mods (those I've coded from official) to offer both.
Upload stability shows at it's best when tested with power shared full files with no other upload oriented stuff (online gaming, other p2p, sending emails with uploaded attachements, etc.) - the figures in terms of upload sessions success rate and average upload per session are the best.
If you can supply verbose log (with detailed upload / download events enabled) of the 5 minutes before any long lasting (above 5 minutes) drop of upload bandwidth utilization it will be great - however make sure no other upload related stuff is on at such times.
For accurate compare - one needs to operate both at same time from evenly powered boxes (physical or virtual) connected to the same equipment with same upload / download files list.
As for your suggestions :
1. if coded well, slot focus and slot limiter code shouldn't hurt each other (just harder to code ...).
2. there's no such thing "simple pure zz slotfocus" - it is a comperhensive change with changing at least all network related stuff (this is why on zz based mods, upload line is straight regardless of other upload using applications - at the price of all other network related stuff at computer responding sort of hanged). On most cases it also involves zz upload and download managers (or parts of them) which totally changes mod concept. WiZaRd posted he was asked (and accepted) to produce a ZZUL based mod - and he is way more skilled than myself, so I suggest to wait and see what he'll release.
As for AcKroNiC mod functionallity - those are decided upon by AcKroNiC "spirit holders", I'm just coding (I do suggest changes - however I'm only advising), as for SharkX I'm calling the shots ...