I have both a Frogg Toggs suit and a heavier, designed for Motorcycle use, rainsuit. I think it's a First Gear, but I don't have it handy and I'm not positive. They each have advantages and disadvantages.
The Frogg packs a bit smaller, but not by as much as I had hoped. On the plus side it's lighter, and it breathes, so in hot weather you don't end up soaking wet from the inside On the negative, the collar doesn't seal as snugly, so in a long ride in heavy rain, water will find it's way in. The zippers on the pants don't go very high up the leg, so they're harder to get on and off over boots, and the leg zippers have no flaps over them, so they leak.
The motorcycle rainsuit keeps me dryer, period. The collar can be snugged down to keep water out, nothing leaks, the pants go on and off more easily. And my jacket is yellow, but the pants are black so they don't show all the road dirt. Frogg's come in one color top and bottom, so if you opt for a bright color for visibiliy the bottoms of the pants are filthy in no time.
On the downside, though, the plastic rainsuit gets HOT when you're riding in warm weather. It's vented, but behiind an ST's fairing the vents don't help much. On a hot day you can end up getting wet just from the sweat.
I keep the Frogg in one saddle bag all the time, in case I get caught. But if I know I'm going to be riding in the rain, or I'm taking a long trip, I'll take the plastic suit. It keeps me dryer.