This isn't written in stone... it's not gospel... it's not "the way things are"...
It's just my experience based on the 7 years, (first few were floundering accomplishing nothing), a mil in online sales and now 93 clients (many of them in niches other than IM)...
The IM market has proven the lowest conversion for opt-ins, lowest conversion for ACTIVE affiliate recruitment (you can sign up affiliates easily as there are hoardes of them, but they quickly get distracted so getting them to active status where they are actually promoting is a much more finessed process), and lowest sales conversions.
I posted my take on this in my recent "I Quit" report (direct/free download at www.IQuitIM.com if interested) ... but it would be good to hear from other marketers who are selling in industries other than IM.
What niche are you in (if you don't mind sharing)?
How many years in the niche?
Did you ever also sell in IM and how did that pan out?