I have pauters that are machined to accept both 17mm and 19mm bearings. Not really worth having a 19mm bearing, unless you are going to be putting a very serious load on the engine for a long time. 17mm handles 500+ hp very well. 19mm is just an easy way to spend double the price on bearings
If you can get the wider bearings, why not? That's the route I went, but I don't know if it is absolutely necessary.
These pauter rods have seen abuse like you wouldn't believe.