I'm new to this forum and i am looking for my first used Mezzo. I really want a D9 as I use my folders for touring as well as commuting and the extra gears are essential. That said there are more i4's around and they tend to sell for a bit less. Is it feasible to convert the i4 to the 9 gear system found on the D9 and is it cost effective please? I have mechanical skills but I haven't done much beyond routine maintenance and tuning on bikes. Sorry if my question is naive , but we all have to start somewhere.