I think I'm right in saying you make less progress towards levelling when using a skill trainer, so does that mean by using skill trainers you're reducing the potential max level that you can reach?

are you sure?... it didn't seem to make any difference when i used a skill trainer

Skill trainers don't effect how fast you level. The problem is that when you train several times in a row then there is just one box that shows the total advance towards the next level, while you can see up to 5 messages that say your rank has increased. This makes it look like you don't advance as much, but in reality, you really do.

Skill trainers increase a skill level by 1 point, this doesn't stop you from reaching skill level 100

Ah k, thanks Fishy.