I had the OFNA kit before I got the Hudy tool - Please don't take this the wrong way, but IMO the Hudy tool is a better option - that's why I upgraded.

Check out the Hudy tool at http://www.hudy.net/xhudy/products/p...db052bc81f8682

I found the OFNA tool very handy, and the sliding hammer worked fine, but only if you seriously heated the case.
With the Hudy unit I still heat the case slightly when I can (ie in the workshop), but if you need to do a track side bearing change the Hudy tool is far superior. It pulls the bearings with no effort what so ever - hot or cold. The expanding finger that pulls the main bearing out is a better design. It goes through the bearing further, and locks the inner cage much more securely than the OFNA one. The pitch of the threads on the removal sections makes for a slow smooth extraction, hot or cold.
It also allows you to fit both main and front bearings together at the same time, as well as coming with a collet adaptor for doing RB style 13mm crank motors (a 12mm extractor and installation guide are optional extras, for 1/10 on-road motors).
Both are good tools. If you are only doing a few bearings a year for yourself and a couple of mates, the OFNA kit is cool. If like me you are changing quite a few sets of bearings, the Hudy engineering, and the versatility and speed of use of the Hudy tool make it a better option.
None of the Hudy stuff is cheap (like their drive pin tool etc), but they do make excellent, strong, long lasting precision tools that do make the job easier, which is why I reckon their stuff is worth the extra $$

Trey - in your position, where you are probably doing lots of bearing changes and engine re-conditions like me, the Hudy tool is a no brainer. It's just so much quicker and easier.

NB: The Hudy tool is very similar to the GRP bearing tool that was around a while ago, until they burnt the factory down and destroyed everything . I think they are on the market again now, but are way more expensive than the Hudy unit (but also include a sleeve puller etc).