I've spent a lot of time this past month working on the same problem. I had both an AK and a Mossberg shotgun I needed to setup lights for. Needless to say, I went thru a few different setups before I settled on what worked best for me.
First, I thought I wanted a tape switch. So I got a cheap little setup that included a 6P knockoff and a tape switch. After playing with it for a few weeks, I decided the tape switch wasn't the best way to go. For me, I wanted the ability to turn the light on, and keep it on. Since you must keep pressure on the tape switch to keep it on, that wasn't going to work. Plus, there is always the possibility of accidentally squeezing it in a tense moment and acitivating the light, with I didn't care for either.
I ended up going with a Brinkmann Maxfire host with a Q5 drop-in. I almost ended up with a G2, but decided the Maxfire with the momentary on AND the click-on worked better. The G2 has momentary on, just no click on, so you'd have to twist it. Again, not as simple as the Brinkmann. The Q5 light is plenty bright, bordering on too bright for inside use. Outside, it's just right. Being an LED, it's inherently more shock-resistent than an incan. It also turned out to be a lucky stroke that the click-on tailswitch on the Maxfire is exceptionally stiff. It all but eliminates the possibility of accidentally clicking it on, while using it for momentary flashes. Viking Tactical makes a wondeful off-set mount for flashlights, that if mounted on the side rail of a free-float handguard, puts it in a perfect position for your offhand thumb to activate it.
For a total of $35, $15 for the Maxfire and $20 for the Q5 (can be had for $10 thru DX) , I ended up with a perfect setup for both my shotgun, and my AK. I liked it so much, I bought a second set of each.
Just my 0.02