I have a weak- western grip on my fh and it is one of my strongest shots. So I may be able to help a bit.
You need a pretty fast swing speed with this grip to take advantage of the spin this grip offers. You really need to whip up the back of the ball from low to high, and you will be amazed at the spin you will get. Once you get the hang of this, you will be able to hit some great short angles.
Low balls are more difficult with this grip, and me being a taller guy at 6"3, I end up using the reverse forehand alot. Just make sure you bend your knees and use that spin to bring the ball up and over the net.
Also, just a question, why are you switching grips? ProgressoR has a point. For me and people like LeeD the western feels natural, but were a minority. The SW is a helluva grip, its not bad at all.
All in all, it just has to feel natural.