I don't think I will loan out fast trainers to lower level teams because of the impact of club level to training efficiency.

Actually, I understand the advantages you mentioned. I also like your idea to restrict number of loans. But, to make the scheme fair, I prefer there is a limit of total number of loans per season and a restriction that only 1 loan deal to another team in same season.

I also wrote some rough ideas on this in this old thread:
http://forum.topeleven.com/suggestio...rs-tokens.html