The only time it would matter, as i see it, is if a coin is mined just a few minutes, so that a small miner does not even get one share submitted. But then again, it would not be a big deal, statistics dictate that what you lose in one period is made up for in another. So all you loose is the difference between profitability between the two coins mined.
For faster coins, if you cannot submit 1 (high difficulty = 512) share, you get paid nothing. So if we mine those coins for 1 hour, the slow miner will earn nothing during that period.
Is that share mined by a single GPU or is it distributed by all GPUs in one rig?
Sorry dude but you are completly wrong (for this pool).
There is a BIG Difference while using 128 diff <> 512 diff.
Just example numbers: A 600khs Card needs avg. 20sec to generate a >512 diff share.
Unfortunately the Pool is mining a Coin with ~10-15sec blocktarget.
As soon as a new Block is found your current work instantly gets USELESS and your card starts hashing on the new block.
(10sec ++ of work lost, 0khs submitted to the pool due high share-diff)
If we had this pool working on ~32diff the card would have been able to create some x32 Diff-shares and
sumbit them to the pool.
There should be a vardiff adjustment while swiching to coins with fast block-target.
I mined for ~1 day here and just saw my cgminers reporting stales and 'work restart from pool'.
RIG is a 3x7950's machine running avg. @ 2130kh. It is submitting a ~1970WU on litecoinpools,
here i get sth like 1500WU which underlines my argumentation.
Just my 50cents