It just seems to still contain a certain amount of luck factor (that I though the pool was supposed to resolve) when a new block starts.
You are right. Whole mining is still about luck, even with pooled mining. Just solving "difficulty 1" blocks (=shares in pool) gives you more steady payouts than solving full difficulty blocks. So yes, missing reward from some round is still fair, because in longer average (day?) you still hit the same number of shares.
Simply said, with rising pool hashrate, members with constant power will earn less from every round, but more often. But this does not affect your daily reward.
Example: When I started the pool, I had round reward around 15 BTC for single HD5970. Now, with 4x 5970, I have much lower round reward, because my hashrate is smaller fragment of whole pool rate. But my daily reward is still correct.
So don't worry about round rewards, when everything else is fine.I.e. If a block is solved, check pool connections for past "n" block versus current pool connections. If a miner is still connected and hasn't submitted a share for the new block but has submitted shares for the past "n" blocks, give them credit for the current block?
Solving one share indicate that miner is working. Calculating rewards based on connections can be misused, because somebody can just connect to pool, but does nothing.