wanted for Backpack hunting Colorado preferably Down,but tell me about synthetics needs to be light,compact,warm.  
what do you guys use? what your opinions and what would you recommend?

Thanks Andy

Down is no good, once it gets wet you are out of luck.  I have a Peak One mummy bag and it is great, lite wt and packable.  I used during -20 in AK and never got cold.

down is great for winter use but like said when wet it will never dry, if you go with down you must pay absolute atention to dry packing and tent floor,  the poly bags will still keep you warm when wet and you can actualy wear your wet socks to bed and they will be dry in the morning and so will your bag.

wingnut, sumed it up, are you willing to put your life on it?  A good quality sleeping bag is worth the money and last you a lifetime (or till you grow out of it).  Another good investment, even when using a tent, is a sleeping mat, get's you up off the floor and added insulation (good place for clothes and socks to be warm the next day, between the two).  Can find a cheap one at army surplus.

I like Wiggy's bags.  Used them in sub-zero conditions and when wet -- always stayed warm.  And I agree with toddster -- get something like a Thermarest.  Worth their weight in gold.

all of the "pro" backcountry elk hunters use the Marmot Helium 15 degree down bag.  pack weight is a little over 1lb.

yip Closed cell foam mat is a must for me.
ok so down is not the way to go if it get wet (which is defiantly a likely possibility)  
been looking at the Wiggy's bags they look good.

BIG AGNES.....LOST RANGER.  CANT SAY ENOUGH ABOUT IT....

I 2nd the notion about WIGGY's bags.Best I have ever used and I have had down,hollowfill etc.
Let me know if you need tell #.

I have a Sherpa Gear bag, minus 40 rating, synthetic fill, mummy style.  Not too heavy.  You will get to see it at the Texas Sweat in a couple of weeks.

I'll go against the grain..I use to do a lot of back packing. Tried most of them at one time or an other. My vote goes to down for weight,packability and warmth. Don't let it get wet. Pretty simple.

I'm with rappstar and Mike--I would go with down, especially for your situation.  I have a zero degree Marmot and its just fantastic.  

But, regarding synthetics, the new Climashield insulation is supposed to the latest and greatest.  TNF uses it in their Snowshoe and Cat's Meow, 0 and 20 degree bags, and I've recently seen the Cat's Meow on sale at REI for $99.  I've owned one and known others who've owned them and have been happy with the fit and feel.
If money wasn't an issue and I had to have synthetic I would buy a Kifaru bag.
I have, and known others who've had Wiggy's bags, and they are also tried and proven.  

If I knew I was going to flip my raft or spend a week in the rain in Alaska I would absolutely go with the synthetics.  Otherwise I would go down and take the xtra precautions to keep it dry.

If you are in so deep that you cannot escape alive because your down sleeping bag got wet, then you just might want to work on your survival skills and not take gear that makes up for that lack.

Wingnut, I am sending you a PM....

I use a Northface cats meow with a compression sack. Very small less than 2lbs. It is rated to only 20 degrees but in Sept I don't have problems. I wear long underware if necessary. I love down and like they said don't get it wet. Look at Northface,Marmet and other top names. There is some great stuff out there. I have a Paul Petzel synthetic mummy bag for real cold weather, it's only 30yrs old but still a great bag. You get what you pay for

My vote is for the North Face Cat's Meow (only one I have used), won't break the bank, good to about 35-40 deg. for me, then I have to layer. Used it this past year in Colorado during elk season. Be sure to have some sort of pad to insulate you from the ground.

I live in Colorado and do a ton of back country hunting often for days. I use the marmot helium 15 degree bag it is down filled and is an awesome bag.

I highly recommend the Marmot Pinnacle.  It's a 15 degree down bag and it is true to it's rating.  I've spent a lot of time hunting CO highcountry in Sept and this is by far my favorite bag.

I'd definitely go with down.  I own both down and synthetic bags and nothing beats down IMO.

North Face Cats Meow.  I used this bag on a bivy hunt in Wyoming last fall and was very pleased with the performance.

I like the Big Agnes bags, but I don't like feather down for any location I'd backpack when things can get wet. For me, it's not worth the little amount of space and weight I'd save.