Not sure why this thread has surfaced again.
The UK xls were cleared to fly almost 2 years ago following the LAA being involved in clearing some structural modifications to beef up the centre section, balance the ailerons and some ther minor changes (trimmer etc).
Zenair later came out with a more thorough re-design which beefed up the main spar, rear spar, centre section etc. The various European regulatory authorities took various bits of these modifications and made them compulsory. So there is little commonality in the modifications required aparet from the aileron balanacing.