Most of my training is outside and event-specific so I should be ok. I also use the same bike indoors and out so I won't be doing wheel swaps any time soon. I guess I could fill the training wheel's rim up with lead just for shits and giggles.
yeah I reckon the actual difference it would make to your training would be pretty minimal, in terms of muscle development/training. It just might make it tiny a bit less horrible if it doesn't feel like riding through treacle...
Depends:
If you want to train for hill climb like efforts then no, probably not.
If you want to train for flat, fast efforts then possibly.
Or you could just go ride outside - on the flat or up hill :)