I forgot to add: the big deal about the Ilford washing method is actually in the fixing, not really the washing itself. If you have a look at the info on the page, you'll see that the fixer used is very high strength but used for a short time. This stops it soaking into the paper and means it's quicker and easier to wash out.
If you are concerned about the permanence of washed FB paper, the best thing to do is buy a hypo testing kit - I think you can still find them on eBay. They are basically a 1% solution of Silver Nitrate, so you can easily make your own. You drop a little onto the washed paper and the colour change shows whether you have washed enough. It's important to get the fix out of the prints, but you don't want to to be wasting a load of time and water excessively washing them.