Bookworm,
As I am sure you know the standard ovation 2 max fuel is 89 usg and MTOW is 3368 lbs. I can't remember what the empty weight of N192JM is off the top of my head.
My aircraft has Monroy long range tanks (takes capacity up to 120usg with a 10lb weight penalty) and my rule of thumb is:
Useful load is 3 big adults and 100USG + bags or 2 big adults and 120USG + bags.
This is with the TKS reservoir full of deicing fluid.
Addition of the Hartzell 3 bladed scimitar prop has given the newer ovations much better T/O performance and I have departed with 30mph + wind on the beam (and a very concentrated look on my face).
I flew the 2 propeller bladed ovation (in Dallas in 2003) and takeoff performance was nothing like as good.
I prefer 900m of tarmac as a minimum - more so for landing than takeoff due to Mooney "float" - very low wing with big flap in ground effect etc...
I have never taken it into grass (I go by helicopter instead for pvt-pvt trips or anything less than 120nm).
I love this aircraft, next one will be a TBM or a VLJ (if I win the lottery).
SB