Having said this, I do like this piece more than not, especially the dial, that I find just stunning in that cream color. It stands out, IMO, among most other Patek PCs, save the 5740.
On the flipside, I'm not particularly into PCs, and while I've noticed a timid increase in interest for this piece, it probably never took off completely. But again, this has been the case with most ACs or PCs (outside the Nautilus line) for many years now, and I'm sure you know that.
In terms of value, you'll probably cut pretty much even with a 5320 today, so this is a fairly neutral factor (notice that the market offers seem rather steadily at a 5 to 10% off with respect to the MSRP). If you go for it, then certainly an AD would be the best choice, and with a reasonable 10% or so off, you would take home a grand complication at a fair price.
Hope this quick reaction helps you make a sound, but very personal decision!