I have bought a HP704 few month ago and I am quite happy with it.
I have the white version, and it is stylish. My 8 years old daughter play sometimes (very beginer) and the piano seems well adapted. Perhaps the scores are slightly too high but it doesn't seems to be a problem for her.
I have compared it with other models in several store:
CLP 635: Not bad, but the touch is less good the roland PHA50 in my opinion: less pleasure to play, perhaps because it's too heavy or more plastic.
CA48: like it very much, but the lack of line in and the reduced control panel was a no go for me.
CA58: excellent, but slightly too expensive for my budget. I think I prefere the PHA50 compared to the GFC. The sound of the CA58 is probably better, but in a side by side compareason I had more pleasure to play on the HP704. Seems more responsive. It's perfectly subjective of course. If the CA58 was at the same budget than the HP704, I don't know which on I would have chosen.
I have not compared the HP704 with the LX705 because I doesn't want to spend the extra money and none of the store I visited had a LX705. Sometimes I regret it. I like the sound of the HP704 but I would not have been against an improved one
If you like the LX705 and the FP90, I am sure you will also like the HP704 because it's the same action as the LX705 and same sound generator as the FP90.