Speaking purely from a point of no experience of either player, I'm going to say I very much doubt it's worth spending out on the Panny over your existing Sony. Even WHF's review of the Panny states it's 3D performance is the most enjoyable "if only by a tiny margin" and reviews of the Sony suggest it's a decent 3D player in its own right.
Certainly you should at least try the Sony beore looking to upgrade it! If you're not happy with the 3D performance, then maybe it's worth taking a look to see if things can be improved, but until then I really don't think it would be good use of your money.