But try explaining to the minimum wage gorilla in Immigration the difference between an IMCR and an IR. A point made often by FFF, is that no matter what the rules are, your entry into the country is entirely dependant on the MWG. If he got out of bed the wrong side that morning, you have no recourse or right of appeal.
Personally I would get a visa for all training. Because the decison to admit you has been made by the embassy and not the immigration department, they can't be held accountable should you be a problem child. Which means they're more likely to let you in.