Interesting spread of views. On the whole actuals will cost the budget more as people will not generally impose any self discipline on their spending habits if it is all to be reimbursed so long as it meets the 'eligibility' criteria. That is why it was dropped last time around.
I work in a mixed Service + Civilian organisation where we often travel together. The civvies want receipts for all meals (and can claim up to half a bottle of wine with dinner) and claim back total expenditure afterwards. My claims go to Uxbridge who scrutinise like mad, even though I'm the budget holder, and then pay up without a murmur. My RN colleague sends his to HMS Nelson (I think) who scrutinise like mad, argue the toss, scrutinise again and then write to me to check that I'm happy even though I countersigned in the first place. My army officers are only in the Service as a hobby and for something to do between managing the family estate and adventurous training so don't bother claiming!