I'd heartily recommend the PX70, did plenty of research myself (had started out looking at LCD, converted to Plasma and decided that in terms of picture quality vs price, the Panasonic was the best package).
Mine arrived yesterday, connected to standard def Sky+ and I'm delighted with the picture quality. It also looks superb (I have the CAB version).
Bought mine at John Lewis for £1149 pricematched down vs MRM - it was originally £1398 (£1099 for the TV and £299 for the stand). Excellent value with a 5 yr warranty.
Re alternatives, I also looked at the Pioneer 427XD but that was several hundred £ more for what looked like very similar picture quality.
You can either negotiate the PM before you order or you can order first and then negotiate the PM within 28 days of placing the order. You need to contact the "undersales" department in your chosen JL branch.
I did the latter. Ordered and paid £1398 a couple of weeks ago. Then reviewed these Forums, found out that other John Lewis branches were pricematching the 42PX70 at £899 (vs the £1,099 JL list price that I had paid) and went back to my JL branch (Cribbs in Bristol). Not a problem, they agreed straight away and I got a refund. Great service.
The difference is that JL both pricematch and still offer the 5 year warranty, which is pretty damn good if you ask me.
There is a specific JL pricematch thread - check that out.