Hi Matt,
I too have a Pug 307 HDI 2 litre, 2002 model. I've been running it on BD (mainly B100) for the past two years (about 30,000km).
I have followed with interest your comments on the high pressure injection pump as about six months ago my car stopped and had to be sent to Peugeot at Dandenong (Victoria) as my local mechanic could not determine the fault on the computer diagnositic machine. Anyway they simply said that it needed a new HP pump and so they replaced it for over $2000!! I asked to get the old pump back which seemed OK to me and was not seized, etc. Perhaps it had seals which had failed and this lead to Peugeot replacing the entire pump. I was pretty disappointed that an entire pump needed to be replaced for over $2k. The mechanic there was not too bad and said that he didn't think that BD had caused the failure, but having said that he could not say why the pump had failed, other than the computer told them to change it.
Would you suspect that the BD might have effected the seal(s) and hence caused failure to my pump? It is a Siemens one as had been mentioned in this thread.
I haven't done the other changes as you mention - i.e. the fuel bleed lines and the sealant around the fuel filter.
Anyway, please let me know if you have any information on suitable replacement seals for the Siemens HP pump. I would be keen to get these and have my mechanic change them out.
Cheers Nick.