I don't know why you say that every effect in reason needs a new channel. I create for example a subtractor and I can put as many effects as I want and they will go on the same channel as the subtractor. You can use 14 instruments in one 14:2 mixer in reason and send them in FLStudios mixer in individual channels. If you want to use more than 14 instruments in reason, simply create 1 or more mixers.
You don't need 1 channel for every effect. You can use only the main instrument and send it to a channel in FLStudio and use the effects of FLStudio instead of using the effects of reason
Watch my tutorial, you will understand better what I mean, make sure you read the video info/description on the right for more detailed info:
http://uk.youtube.com/watch?v=JDednzESz-Y&fmt=18