I think that for current reward table and difficulty retarget algoritm the n-factor increace is unnecessary.
Increase of n-factor lead only to extra heat from GPU-memory and dropped stability of GPU-mining.
The dropped hash speed not affect the miner's reward, as blocks are solved in equal time intervals.
And if your hash speed was 5 Mh/s and now it's 0.7 Mh/s, your reward will be the same, as all miners got the same speed drop.

Only thing that it serves is resistance to create of ASIC for that hash algorithm.