I have several Emersons and rate them highly. However, I'm not entirely convinced about the Wave. It is not a foolproof device. It tends to work best in jeans, less so in chino type pants. The thumb disk or Spyder hole is pretty damn fool proof. Fortunately on Emersons you have the option of both.
My opinion on the gun vs knife debate is this: strapping a gun on every day is a fairly big step, unless you work in law enforcement or related security type work. Carrying a knife is a lot easier IMO. The best SD weapon is the one you have on you at the time, a statement so oft repeated it is practically a cliche.
The whole issue about a knife having a poor image as a SD weapon is a bit silly IMO. If you're involved in a SD situation and have to shoot someone, do you think the cops will look at you differently than if you used a knife? Any situation where someone is wounded/killed by a deadly weapon (whether it be a baseball bat or an assault rifle) will be the subject of a police investigation. If you have a legitimate reason to use your weapon, ie, it is a justfiable case of self-defence, you will be exonerated. It is very advisable that you have a good working knowledge of the law governing lethal weapons in your state though, before you start packing a gun or knife.
I believe most people are more likely to slip a knife into their pockets when leaving their homes for the day. However, there will be times when you will want to pack a firearm. So why not get both?
I would recommend the Glock 26 and Benchmade 710 as a great starting point for SD. The 26 is a great little gun, is easy to carry and shoot, and offers 10 rounds of 9mm para. The BM 710 offers the axis-lock, D2 steel, and a great blade profile for self defence, and other more mundane chores (which will be what you use it for most of the time).
If you feel you'd like to spend a little more on the knife, by all means get an Emerson. I prefer the 8, 11, 13 or PSARK. Bear in mind though most Emersons are large knives and are not sheeple friendly./
Mark