Think you may be on a hiding to nothing to find suitable software to decode the files.
Surely the easiest way is to buy another working SONY RDR-HXD710 on eBay, swap the drive out and record to DVD. Seem to be around £75 for a working model.
Once you've backed up to DVD to use on your new Panasonic, you can resell the Sony for a similar amount, less fees of course. Only other cost is 20 odd DVDs, which are as cheap as chips nowadays.
Probably the easiest, cheapest and least stressful solution to your problem.