Paranoid about Turbo Failure !!!!!!!

[Horizon]

Hi Folks
I am now paranoid about turbo failure. My best mate's 520d engine blew after running on full revs at the side of the M61 motorway after the  turbo seals gave up on his 07 5 series. Ive had several petrol BMW;s with no engine worries, but after buying an X5 3.0 D ive beed horified by the problems that I have read on here and other sites.
I am considering changing the turbo, for a new unit. I enquired at several places today and was advised that my turbo could be either an electronically controled one or a mechanically controled one, how do I find out which one off my vin number LX23929.    2006 (55plate Sport )
Am I over reacting ?? Its got 98 K on the clock FBMWSH, and ive got a vortex C/case breather and have changed the oil at 6K and air and oil filter, Castrol Edge Turbo Diesel from Euro car parts. No sign of blue smoke, only a bit for the  first second when cold starting.
I have been told that the OEM turbos cant be repaired/remanufactured.
Please can I be put straight on this matter, as I dont want a 7 grand headache. I have been quoted 695 + VAT for the mechanical turbo and £810 +VAT for an electronically controled one.
Thanks in advance for any help/advice

[Horizon]

Sorry, posted on wrong forum, I have reposted on E53 Forum.

Thanks