Which pooled mining scheme is better in terms of constant mining? I'm comparing gash.io with slush scheme. Say I mine 24x7 without pool hopping at 5GH/s. Will the BTC amount be the same if I mine at slush or gash.io. And what if I get disconnected from either of pools for say random one half hour duration or more a day, how would the reward be?
I think it will roughly (~1%) be the same, otherwise no-one would stay at Slush or GHash.IO, if one of them has obvious lower rewards. In your previous question I answered that there are differences in the way your share is calculated, and thus the reward changes. But because you don't want to hop pools, score will be the same as PPLNS. Otherwise you can try to mine a week in both pools, and see the reward you get in both pools. I think it is best to try it yourself. You get bitcoin in return, so it is not for nothing. 

I'm not sure how the disconnection works with the score-system, but I think PPLNS wins on that area, because you won't get penalised. IN PPLNS you'll just get paid for each share you contribute. So if you mine 100 shares/hour, and you are offline 6 hours, you'll miss 600 shares. Depending on the btc/share, that exact amount of btc is what you miss during your offline time.