I run some half the price of DS2500s Hawk fast road pads in the rear and they suffice, so long as they cope with the temps asked of them on a track day without crumbling then that'll do. They do this fine. Much as I love the DS2500s, they're a waste of money on the rear TBH.
The OEM rear pads I've had fall to bits on my MKIV on the track in the past, so I just bypassed them this time around and swapped them... they may well have been fine??, I don't know and didn't want to find out.
I thought about the upgraded rears to R32/S3 spec for a long time and I decided they weren't necessary on my car for my style of driving and its usage. I, like Jabbalad, like a loose rear - it isn't for everyone and its taken a long time to get the confidence to use it to my advantage, but I wouldn't like to change the dynamics I have now. For everyone else, then it's a perfectly good upgrade and in terms of value for money the best you can do to the rear.
Dave mentioned some DS2500 issues we've been talking about on UK-MKVs, this was just involving some of us who track our cars, not a 'free for all anecdotal moan'. Those with solid discs were finding that the pads were crumbling away and the compound changing thus damaging discs. Essentially it is down to the temps getting too high on them, they can't cope with a big heavy car and being stamped on constantly for seven sessions at 20 minutes at a time. They're excellent pads, but they can be taken past a limit of working effectiveness on a track. There's scoring and deposits left on the discs.
I haven't had this, but I have had the edge crumbling issues (see pic below from a set used at Oulton last month), it hasn't worried me enough to not replace mine with a fresh set of DS2500s, they're on the car now. The others are looking at the Pagid Blues (£200+ a set, so it isn't a cost factor) and some Mintex race pads simply to see if it suits them better? I've run out of my DS stockpile though, so I may look into some other options myself in the future.... getting a pad to do everything you ask of it road and track is extremely hard, a bit of experimenting is what's required. I may go to a 2 pad set up, road and track.
For the 'Ring, it isn't a brake heavy track, you use them a few times and there's plenty of cooling time in between - I haven't heard of anyone experiencing DS2500 issues there. For the road too, they're still my personal choice. There's nowt wrong with them and they're plenty better than 90% of others you can buy, but a track day is proving a bit much for them on some set ups.
Brake ducting is an avenue we're all going down to help that way, a detachable carrier mounted bracket to run it on the face of the disc, more on this when it is looking realistic/proven. Other options are being looked into too.
Right, the pad off my car. See how the edges are all crumbling away? The compound on the very edges has changed and is brittle, the others had this happen to the whole pad and big lumps were coming off... not good. Proves how much cooler a 2-piece disc runs though.