Prop reamers are a good thing for your flight box. If you go for a two stroke engine then the one you linked is a metric and not the one you want that would be this one:

http://www3.towerhobbies.com/cgi-bin...?&I=LXEGH7&P=7

The vast majority of two strokes have SAE shaft sizes of 1/4 or 5/16th inch. When you get into four strokes then the Metric Reamer will need to be added in most cases.