I'm puzzled here ... I had line6 stuff since years(spider 2, spider 4, JTV variax, pocket POD, Amplifi TT).
So when Spider V came, I bought it after checking 1 important point: I had the FBV Express MkII, working perfectly with the Spider IV, with 1 feature I loved most ... guess which ? controlling the looper.
So I came here, saw this topic, esp the affirmative reply from NickBell which was the last answer at that time , and also the " Complete Line 6 Pedal Compatibility FAQ" http://line6.com/support/page/kb/_/effects-controllers/fbv-mki-mkii-controllers/the-complete-line-6-pedal-compatibility-faq-r58
The latter says: ... compatible with Spider V ... It does not suggest ' partially compatible ' ...
So on 11th of december I placed my order, then waited several weeks ... and now, guess what? The pedal is of no use with the looper.
I forgot to mention that I did not envisage to use extra 100s of euros to buy a 'even more compatible' pedal.
I wouldn't call this good commercial practice. Would you ?
Had I known that 'partial compatibility', I would not have bought it...
Maybe I'm wrong and perhaps NickBell you have some material elaborate on your first answer ? You would save my day ...
(Apart from that, it's a really good sounding amp ...but with lots of bad presets ... well at least for my taste)