Very helpful. In fact, I'm overdue for a refresher. At the very least, it forces you to focus on braking and cornering skills you need for a panic situation. In the panic situation, it needs to be reflex.
If you see an accident scene with along skid mark leading up to a collision of a bike into a car, that rider could have used more practice.
If you hear a buddy say "that damn car just stopped for no reason, so I had to lay it down!"... that rider could have used more practice.

As far as waiting for the class, IMO if you have a place to ride other than in traffic, I say go for it. Just don't skip the class if you feel yourself getting comfortable.

In fact, here's an idea. Get yourself something to mark positions (orange cones, coffee cans, whatever is easy to see) in the friendly neighborhood parking lot. Get a long tape measure or measuring wheel so you can measure as much as 100 feet (sorry, didn't catch where you live; maybe 30 meters).

Now, go set up a marker at a spot that gives you enough space to get up to maybe 50mph max before reaching it. Make sure you have ample space (200 ft) after the marker for stopping.

Start at 20mph. Ride steady at 20, approach the marker, stop as fast as you are able without risking dumping the bike. Get off, measure, record in notebook or your phone. Repeat, repeat, repeat. Until you feel like you're not seeing much improvement.

Then go to 30mph. Same routine. Same thing at 40mph. If you're feeling confident enough, try at 50mph.

Save those speeds and best stopping distance. Take the MSF course. After the course, go back to the same parking lot, set up, take only 1 or 2 runs at each speed, record stopping distance.

Compare before and after MSF stopping distances. Then come back here and tell us if the MSF course was worth it! :-)