Hey,
Im in the UK too, and I started off on Sustanon for the first 8months, then switched to Nebido when Id be going abroad for 10 weeks.
I prefer Nebido in the sense that, I have my shots every 12 weeks as opposed to having the hassle of getting my Dr to inject me every few weeks (although I have been asking to be taught to learn to self inject for about a year now! :p).
Ive not experienced any negative effects with nebido, no ill effects or reversed effects i.e no "shark" week, or whatever nickname it may be called, has come back.
It all just seems much more convenient.
I do think that having it done every 12 weeks, as I do, has me with my T levels at a constant low though. I have had my levels checked and they come out as 15 something or the other, and the woman at my clinic says it "should" be between 18-29, but she wont change it. I dont know, I dont really get all that, but other than me thinking my levels are abit below average, Nebido is fine. It makes life easier as Im looking at what, 4 shots a year? Thats great, less hassle, less reminder of what Im going through :p
I wouldnt worry about it. Aslong as youre levels are being monitored and checked on, there shouldnt be a problem.