I need to replace my rims (Open pro) soon so I've been searching around the internet at options. My current wheels are a little porky with 36/36h and DA track hubs.....
You don't say if they are LF or SF but by my estimate
Hubs = ~500g
Rims = ~2x435g
total (less spokes) = ~1370g
spokes can run from ~5g each to ~8g each (including the nipple) depending on length and type; lets say 6g. But 72 x 6g = 432g so the total wheel weight is likely to be ~1800g maybe a bit less if you choose the right spokes.
If weight is your main concern you can go to ~300g for a pair of track hubs (but they will come with allen key fixings and you will probably need a good chain tug to hold them in the right place) and you can lose spokes, say down to 28F 32R (or fewer if you choose the right rims an you have a good plan for spoke breakage) so there is a 70g (or more) saving to be had there. So you could get down to ~1500g without too much effort. I'd have said.
If you go for carbon rims there is a weight saving and an aero benefit (which may be appropriate or not for your use depending on the design) and they can be OK.... but cheap carbon rims can crack up and should you come to grief in a pothole and the rims are damaged they are liable to be both scrap and unrideable. Clincher carbon rims are significantly more likely to be damaged than similar rims for tubs. The brakes won't work super-well with carbon rims, and if you are riding in hilly territory this is likely to be important.
So you can even build a vaguely conventional wheelset that is sub 1000g (with carbon sprint rims) but it is highly questionable whether it would be appropriate for your use or not.
Personally I'd value the repairability and durability of a wheelset not too far removed from the one you have at present over a small weight saving (likely to be 0.5 to 1.0% of the total all up weight...?) but hey, each to his own and all that.
cheers