Drive Line Question

So, after doing some initial research I decided to go from 14/38 set-up on my 06 TLD to a 13 tooth front since the chain is shot and I need to swap it out. I go the TM aftermarket swing-arm slider that is "designed for hot-setup 13th". I have noticed a few places that mention some other issues not to run 13 up front. Something about shaft damage. Don’t see how lowering the leverage arm on the torque being applied to chain could cause an increase in shaft bearing stress. Am I missing something? Is there a concern with going 13/38?