Now before you cringe and start swearing that one will ruin their seals, you need to understand silicone. First silicone can withstand high temperatures. Silicone cookware can withstand temperatures up to 500F. So the temperature of boiling water isn't going to affect it.
I used a small sauce pan that was just big enough to hold one FF mask seal and filled with distilled water. I then added 1 teaspoon baking soda and brought to a rapid boil then reducing to just a boil.
As you can see in the photo, the seals have the usual whitish film. The before picture was after I washed all of them with hot water and Dawn dish liquid and then left to dry.

Now I had to decide how long to boil. I decided that 5 minutes would be a good baseline. So I dropped the first one in with the part that goes against your face so that it was on the bottom. I turned it over after 2 minutes for 1 minute and then turned it over again to finish. I pulled it out and immediately rinsed with hot tap water.
Repeated the above with the other two. Adding more distilled water in between each one. Do not add any more baking soda.
Now for the moment of truth.........
They are once again crystal clear.

I tried to get a close up of them but it didn't work too well. But here is a photo that you can see that it is clear.

As far as stickiness, They are not as sticky as new but do have some stickiness to them. One of them is my Ultra Mirage seal that hasn't been used in over 3 years. After boiling it looks and feels like new.
I used one of the Quattro seals the first night. According to the data, it didn't leak too much.
I used the lot of them the rest of the week, Surprisingly they all worked well.
My conclusion, If you were to boil your mask everyday I think that you would cause premature wear. I believe though that you wouldn't do any harm by boiling your everyday mask seal once a month. Since I won't need these masks until I am sick again, I am going to boil them again and put away.
If you don't believe me, try it with an old seal that you might have. Just remember to use distilled water and baking soda.
Edited on 4/28/12 - Put more spacing in between pics/descriptions and removed before and after water pics.