If you have right equipment, you will do ok (however, like all gold in Colorado, there tends to be a lot more fine gold than gold bigger than .1 gram). I use a Gold Cube and in doing so, use a battery powered pump (1000 to 1200 GPH) to feed the Gold Cube, along with a 1/8 inch (8 mesh) screen. If you run too much water thru it, you will loose the fine (100+ mesh) gold. What this says is that I don't use a traditional sluice (you tend to lose lots of the fine gold with them here). The guys at the Grand Junction GPAA (that own claims there) are finding enough that they use the claims a lot - You really need to talk with them - My trip there was over a weekend in 2011.
NOTE: Gateway Colorado is a town without much of anything there. There is a 4 star resort very nearby and is very expensive (they sell fuel and supplies, but you will want to stock up before hand because of the cost). You can camp on the claims if you are a member of the club (GPAA has general claims here too).
I attached a picture (my handicapped wife is on her scooter metal detecting - in the yellow shirt), Alton Oakes (treasurer of our Colorado Springs GPAA) working the dry washer and and another member of the club looking on. Across the road is the river, as I say, you would need a 20 foot ladder to get to the river at this location (and a machete to cut a path to get to it). The ancient river bed is about 6 inches under the ground people are standing on - that is where were were prospecting. There is cactus everywhere. There are places you can pull off that is right on the river (claimed by the Grand Junction club), but that is not where we were digging (also a claimed site). There was gold here.
A 12 Volt canister vacuum would have been good to have along. The 2nd picture shows that was not much digging to get to original bedrock (we ended up sweeping it up as best we could once you went thru the overburden). Bring a lot of water, you'll dehydrate in the sun.
