PPLNS variance is higher than CPPSRB. The fact that PPLNS can overpay shares is not an advantage, it just adds variance.
One advantage of PPLNS is that you don't have to wait around potentially forever to find out how much you're going to make.
CPPSRB irons out variance as much as possible, with the pool-wide reward average on Eligius sitting right around 98%... which is expected due to orphans. Keep in mind that Eligius has no fee, if a pool has a fee it is taken off of actual earnings, not expected earnings, so earnings would be ~98% minus the fee.
So that 4.72% (with transaction fees you'd get 102.72%) is solely due to orphans? That seems like a very high orphan rate.
Transaction fees are paid towards the share log to try to offset the losses to orphaned blocks, but it is insufficient to make long term 100% PPS viable currently. It does however, help get everyone closer to 100% than normally possible.
Keep in mind that 100% PPS is not statistically possible long term with *any* reward system mainly due to orphaned blocks.
Well, if you add in transaction fees, which apparently you're doing, then 100% is quite possible.