You can do a convex combination of different reward systems. But preferably each of the component systems should be good - if half of the reward is proportional, the pool will be almost as hoppable as a prop pool.
A PPS/PPLNS hybrid can work. It would be similar in some ways to DGM, which one is better is a matter of taste.
I touched this briefly in section "Hybrid reward methods" (currently 7.3) of AoBPMRS.
Don't know if that would work, say there is one miner on Prop and five miners on PPLNS.
Now say all the miners on PPLNS have 10GH, so they find a block and they all get 5BTC (25/5).
The single prop miner has 1GH, but he is the only miner on prop, so he gets all 25BTC.
See the problem?
Individual miners won't be classified as prop or PPLNS. All shares will enter the same database; when a block is found, the reward corresponding to prop for this data will be calculated, as will the reward corresponding to PPLNS. Every miner will get half of each.