First off squirt lube (don't google it) absolutley brilliant, been using it a while but the last few rides it's really proved itself winter proof too. Quick to apply, doesn't fuzz up in the dry, keeps your chain lubed when it's really filthy but your chain is easy to clean post ride (if you bother) As such it's possibly not up to regular river crossings but unless you ride with the bogtrotters it shouldn't be a problem. I tend to re-apply before each ride unless it's been dry out, it's quick enough to do. Twenty odd quid for a huuuuge bottle, email and they'll send you a little sample pot that you can keep in your camelbak for emergencies.
After bemoaning the cost of gold star quality water proof pants I bit the bullet, saved my xmas pennies and bought some endura stealth lites. Money well spent, just a pity I didn't stump up more. These are basically waterproof tights and they are ace. I use them with overshoes and basically nothing gets through, on sunday everybody else had wet feet in the first hour except me, my feet were a little damp by the end but still warm and I'm pretty sure it's the overshoes that leaked, postride I even hosed down myself down and no water got through, brilliant. The only problem is I got the tights so they creep down, I should have got bibs (I normally do) but they were another £30 - would have been worth it tho. I reckon boots with high cuffs like these would negate the need for overshoes too.