Running high current load with 2 5-cell LiPo batteries in parallel
Connecting LiPos in parallel is fine. You can even connect thousands of them.

The worst thing I believe could happen is that one of the battery fails and the other rushes a lot of current into it. The best way to protect against this would be to use individual fuses on each battery.

Furthermore, you can replace diodes with FETs, although I'm not completely sure if it works to "isolate" a battery with lower voltage.