I've used the silicon based spray for several sets of lightweight anoraks.....It would work well for the average light rain. Didn't stand up well at all for the Florida downpours we get. After a minute it leaked right through.....and before anyone asks....yes they received the proper coating and enough was used. It just didn't hold up.

As for waterproofing boots....I relied on Sno Seal. It takes warming the boots a bit and rubbing the compound into them while warm (I don't remember exactly what it was made of) but I had NEVER had wet feet when my boots had been Sno Sealed.

Hope it helps.