i think it is a matter of personal preference . I had always had ancestry but with the 1911 being on fmp i thought i would change this year. as you know i dont llike it. yes i think i have found things not found on ancestry but i am sure it works the other way round too - things are found on ancestry that cant be found on FMP. Occasionally when looking for people in census which have already been given by other researchers using ancestry i cant find them easily.
things i dont like about fmp are :
on front general search page you can only specify name and dob and that will bring up everyone in all bmd , census etc. then when you select a year of census you can refine place of birth and other things. once you have finished with that census and go into another you have to refine it again (if that makes sense) .
i dont seem to find things as easily as i did in ancestry . it always seems to take longer to go through all the census and other records .
In ancestry once you have one census transcript open it puts up suggestions for other census/bmd down the side - sometime this has been useful and found other census i hadnt found - though other times it is a complete red herring.
i also use ancestry to store my private tree and you can add the census etc direct to that which i like. ( though i am very careful and dont just add their hints or merge things without very careful checks)
advantages of FMP - yoou can search census on occupation which can be useful and also search census by address.
i will be glad to change back at end of dec but you might get on fine with it.