The guide is a "light" stability shoe, so you a probably a slight over-pronator.
trail shoes are a bit different. First, most people who run "trails" aren't running anything technical enough to need a trail shoe. Which is why most major shoe manufacturers don't make a technical trail shoe, they just slap a different tread pattern on one of the shoes they already make (Nike Trail Pegasus, Saucony Omni Trail). Most good trail shoes are produced by companies like Salomon, Teva, Merril, Montrail, Northface, etc, and you probably won't find them in your local running store (unless you live in colorado or something).
Secondly, there are a lot of people out there that don't believe that trail shoes need stability b/c your foot strike is so inconsistent while trail running. You strike on your forefoot quite often due to uneven terrain. I'm a neutral runner, so I can't comment from experience whether or not the absence of stability will hinder/hurt you. However, I can tell you that your foot strike on semi-technical and technical terrain is quite variable, so the theory makes sense to me.
If you are running on carriage trails or something, you don't need a trail shoe. I did my 50 miler, which was almost all exclusively on trails in the Vomero. I tore them up, but they were sufficient for the type of trails I was on. There were roots, rocks and mud, but nothing crazy. I definitely could have run it in a trail shoe though.
Anyway, my favorite trail shoe, BY FAR, is the brooks cascadia. Its comfortable, not bulky, drains water REALLY well, and has a pretty good grip, even on wet rocks.
I won't pretend to be an expert on trail shoes, but I've had a few pair and run through some pretty serious technical terrain. The Cascadia will always be my first recommendation.
[This message has been edited by AggieOO (edited 12/31/2009 3:54p).]