James,
Have you had any help from ED clinic or Andrology with why Caverject and Invicorp don't work for you?
Did they work in-clinic?
Have they checked you're doing it correctly?
I can't think that Klinefelter's syndrone would make any difference to these drugs.
If you go ahead with a referral for penile implant, I would suggest you get a referral to UCLH if that's within reach. They do more than half the implants in England, and you don't want it done somewhere that does only a small number of them.