10k would buy you a lovely mercedes clk.

Complete with many visits to your friendly dealer to fix the blooming thing.

Same engine is fitted in Jaguars (S type, XF and XJ) so a visit to a Jag forum may reveal if there are any serious problems.

All cars have their faults - as long as you budget for them what's the problem, the key is buying it for the right price in the first place, then you have money left over to fix faults. They are fairly reliable cars by Peugeot standards, the only thing I'd do is change the oil between services to help the turbos stay in top trim, let the car idle before turning it off (to cool the turbos) and put a few quid a week away for the cambelt change required in 30K miles time. Find a decent independent mechanic, suspension links and power steering pipes are not expensive items away from the st(d)ealers, take the old hose to a hydraulic hose manufacturer (aeroquip or whoever) and they'll make up a quality new one which will last the lifetime of the car for a third of the O/E price, the (probably identical) pipe has sprung a leak on my C5 so I'll have to take my own advice on this one. Mechanically the 2.7 v6 diesels engines are very strong. I do think £10,300 is over-priced for what is not a popular (but vastly under-rated) car.
I wouldn't mind one of these myself.

Make a silly offer and leave your phone number and car details written down to remind the salesman, month-end when they're trying to boost their sales figures to hit targets your phone will ring!

You'll still want the turbos to spool down before switching off. Diesel or not these engines are known to run their turbos hot - perhaps that's why they don't have DPF issues? And perhaps that's why they are not that economical either? Due to slighty excessive fuelling?

Don't ask me why the turbos on the 2.7 V6s run hot - ask the PSA group or Ford. I suspect it's DPF related. Of course they are not going to run hot at idle with modern mapped fuel injection systems, it's not as if fuelling rich in one part of the range will mean it does throughout the range like it was in the "good" old days of simple diesels.

I test drove a 407 Coupe (3.0 V6) last year and it was a lovely car, buckets of space inside, comfortable, nice to drive but its no sports car. Its very heavy and the handling is heavy also, and the controls are a bit fiddly but overall its pretty good, a Merc CLK is more common than Lonsdale tracksuits in the Essex area and as a result the 407 stands out.