If you get one, get the 623FGA with the master kill switch. IME if you dont, you'll regret it (I got the 623FA, and regret not getting the FGA).
I tried the cheap way, but I dont like on/of switches on weaponlights, I prefer momentary only. I also dont like cords hanging in places where I cant tie them down (and even then, I dont care much for them). I fired my 590 once with the light on, and I took the light off if it before my thumb swelled up. That was a big deal to me since I'm cross dominate (left eyed, right handed, longuns are fired from the wrong shoulder) and it was my strong hand that got hurt.
While it was expensive, the Surefire forend solved all my problems. I can fire it with my thumb on the tapeswitch, there are no exposed wires. One complaint is that the whole tapeswtich is exposed, I cant use the switchblocker because I use the front for LH shooting, and the rear for RH shooting. I also wish there was a little more to hold on to, if they'd make them simular to the longer "field" forends we could trim them to whatever length we wanted. Yes, its heavy, but so is my shotgun, so the added weight wasnt a real issue.
Yes, shotgun recoil is hard on the bulb, however mine hasn't failed, yet. I put my spare in before I go shooting, and put the other in when I'm done. However I mostly shoot reduced recoil buckshot (federal H132 00). I'll probably get the P60L (LED lamp) for it soon. It should hold up to the recoil better, but I want it because it solves my biggest problem with surefire lights.
That problem is when the batteries get to a certain point of dead, the incandescent bulb goes out completely, usually at a bad time as well. Its like doing 70mph on a dark highway and all your lights going out because a ground wire came loose. LEDs dim when the batteries are dying, but they still work. I'm thinking about getting a 9 volt tube as well.
As far as weaponlights go, I keep fresh batteries in them. When the batteries die in my EDC 6P, the replacements come out of a weaponlight, and the fresh ones go in it.
Anyway, gun porn entry. Its a 20" Mossberg 590. I had to grind the bayonet lug off to clear the light, but I dont even have a bayonet so it didnt matter. I added a side saddle not long after I got it, maybe the same day. I also cut the stock down and added a youth model slip-on recoil pad and got a 12.5 LOP. I also stippled the stock with a woodburning pen
This post turned out a lot longer than I expected. Sorry, I tend to ramble when I'm tired.