If you've got the Basic 3 already, I'd vote for getting the Basic 7 as your second knife. I'm assuming you're big enough and have enough frame to carry the 7 defensively without it printing through your clothes.
The reason I advocate the Basic 7 over the Basic 5 is that it is substantially bigger and will handle considerably different tasks than the Basic 3. The Basic 5 is sort of like your Basic 3 on steroids. They are pretty much in the same league (whittlers & cutters), but the Basic 7 is larger enough to be in a different category (choppers & hackers). Which means that adding a Basic 5 to your Basic 3 doesn't buy you a lot of new capability. But adding a Basic 7 or 9 does.
IMHO the Basic 7 is a very fine all-around blade. It is big enough to suffice for chopping, yet still capable of handling finer cutting chores if you choke up on the blade a bit. Tactically, the 7" blade puts it up there with the other general purpose combat knives (Randall, Mad Dog, Rinaldi, TOPS, Livesay, etc). Regarding the Basic 5 tactically, I think it's just a little bit short for the job. Plus, I wouldn't want to show up against a 7-8" blade with a 5" blade in my hand. Your training & tactics would have to compensate for the difference in length & reach of the blade. I say, don't handicap yourself that way if you don't have to.
I'm not sure what sheath comes with the Basic models these days. You could query your Busse dealer or the factory for the scoop on that issue. However, if you don't like the sheath that you get with your Basic, I recommend you consider an after-market sheath from Normark at On-Scene Tactical. His design is really versatile and the workmanship is top-notch. Plus his prices are reasonable and he's a great guy to deal with.
Yours in nuclear Basic appreciation,
Greg
