Your links did seem interesting! - however, reading more carefully, the product does just SEEM to be a pretty standard coax (or 300ish FP) with a similar video cam to those we're using now.
The Hubsan I was keen on - despite offering real FPV in an integrated package - is really too small IMO to be a viable contender as an outside platform in any sort of wind. Plus is outside your budget, and not available in the CPR (maybe security reasons? - I remember a few months back one of our contributors ran into trouble with the police in Hawaii flying (with camera) over a nude beach(!)).
And the F45 might bounce around too much for FPV, despite Rexless's great video posted recently.
Why not revisit the idea of the big F39 Coax? It's cheap, stable, and would be very easy to learn. It could also easily handle your camera (plus a small 12v power source or DC converter) and would give you the involvement in electronics you were looking for.
That failing, think your X400 will be a fine choice. But I'll still bounce our ideas off my LHS r/c guru on Tuesday. If money were not a problem, of course -
Only about $10k! Should buy two, so there's a spare handy
PS - from my F39. The little dot at the bottom is me!