Garmin Edge 705 Vs 800 Vs ??

I'm looking at various options for century rides and specifically next year looking to do a double century. That means a lot of waypoints and the less time I can spend lost the better.

So I'm looking for:

Moving map (updatable map much preferred)
Waypoints (the more the better)
heartrate monitor and cadence measuring preferred as I've already got both set up for my 310XT
Sweatproof/water resistant

Touchscreen irrelevant.
I'm mostly looking for the mapping capability so if there's something that does the moving map better please bring it up. These two just caught my eye in a quick look. The 605 seems to be in the ballpark but I believe I lose the HRM and cadence. Not a real show stopper but I'd prefer them.