I assume you mean not having the percentage for Working Area overheads under options C, D and E.
For me, it is more realistic Prices because the risk - which could be both threat and opportunity - associated with this percentage is removed. That might mean higher Prices or lower Prices but - all other things being equal - will probably mean that real costs are closer to Defined Cost are closer to the Prices. This applies to both forecasts at tender and actuals at out-turn.
Suggest you post this on the BuilltIntelligence LinkedIn NEC forum as it is a good point for discussion.
Probably wont alter tendered total of Prices too much, but will obviously affect the fee percentage as the element for recovery of people/working area overhead will now have to be included within the single fee. Therefore you will see a slight increase in that fee percentage (actually you wont as you wont know what it would have been for any future tender) but overall the attempt would be for a Contractor to get back to the same financial point you were with more than one fee percentage.
This is about redistribution of fee rather than additional/reduction. Will be easier to administer, but more difficult for Contractor to get right in the first place in a competitive tender situation.