There is another factor that I think I have picked up that contributes to the loss of income with algo switching on zpool and it relates to the delay between when a new hash is solved and when it becomes "immature". If there are several "new" hashes and the miner switches way to a new algo you lose some of the income from those shares when they switch to immature. This issue is easily observable. simply mine a coin like x17 and when you see 4 or 5 new shares sitting in the pool stop your miner and see how many of those hashes you get paid for.
A more interesting test would be to sit idle until a "new" block shows up in X17, *THEN* start your miner and see if you can "skim" a few % off the block.
I have done that test and yes you can
However its generally still a lose/lose situation as it seems to take a while for your share percentage to build up so your share of those new shares is very low . So you lose a lot when you switch away and only gain a little when you switch to.