Is there a tactical advantage to a vertical foregrip, or is it just a personal preference thing? Do these grips actually make firing and holding the rifle more comfortable, or does it depend more on the user? Finally, are there any disadvantages to having one on your rifle, besides the extra weight?

For me, it makes it more comfortable holding the rifle...and it makes it more natural to keep my elbows in, IF I were to have to chase zombies around my house.  I don't do a whole lot of rapid fire, but the general consensus is that it does help to control the weapon when you need to do it.  

Most of these grips hardly weigh much, so there's not much down side there.  

And, you can use them as a monopod in a pinch, if you get one that's long enough.  

Some folks hate 'em, but I've got one on both of my "grap and go" zombie killer guns.  

Ugh, that was a horible game...my SPURS!

Anyway, I can kind of mentally picture how it would make holding the rifle a tad easier...I never even considered the idea of a ghetto monopod...Maybe I'll buy a cheap one and give it a try. I'm getting a Yankee Hill free floater and a rail or two, so I guess after I build the rifle, hopefully in the immediate future, I'll try it with and without the foregrip and see which I prefer. The foregrip does add a bit of tacticality to the rifle's appearance, no?

Quoted: Ugh, that was a horible game...my SPURS!

That game was great. You don't see that much excitement in the NBA that often. Plus, the Lakers won so all the better.

Ugh...why does everyone like the Lakers? ARG! Actually my only quarrel is with Shaq and Kobe. The rest are ok.

Anyway, anyone know a good inexpensive vertical foregrip I could buy?

Not quick-detach, and not really for serious combat, but if you just wanna do a proof-of-concept, these are pretty decent:

http://www.johnmasen.com/Merchant2/merchant.mv?Screen=PROD&Store_Code=J&Product_Code=1505N&Category_Code=AA

It's almost disposable, but I've still got mine on my rifle. Solid piece, for the price.

Makes it easier "spray firing from the hip" with your "bullet hose".

When you mount a light, a laser sight, a flip up front sight, bipod, GPS, and your laptop on the front of your rifle, its hard to grip it so you need a slim little grip sticking down.