Never mind, I wasn't abstracting far enough. I was thinking blocks:pseudoshares, not blocks:shares:pseudoshares. So minerd won't know, but what's the difficulty difference between pseudoshares and shares so I can estimate?
I guess the difficulty difference between blocks and shares is bigger for the ltcoin pool, meaning I got 4 much smaller shares last night. Presumably after your estimate of 10 hours, give or take (a lot), I'll get one share from P2Pool that's a good deal bigger than the ones I got last night from ltcoin, right?
Current share difficulty is printed on the stats page. Pseudoshare difficulty can be anything, because it doesn't really matter. You can tune both of them by setting your username like this:
BL5vKqnKHmnzvLZ5qCxETNnMzTM6CCdUzf/0.01+0.001
Here, BL5vKqnKHmnzvLZ5qCxETNnMzTM6CCdUzf is payout address, 0.01 is share difficulty and 0.001 is pseudoshare difficulty. However, you can only set share difficulty higher than current p2pool share difficulty, so this is only useful for miners with high hashrate. You can find more p2pool basics here
https://bitcointalk.org/index.php?topic=18313.0