There are alot of options and opinions for the correct way to set up these sleds. There could also be several other reasons (besides clutching) as to why your sled is not climbing the way you would like it too. Keep in mind that track speed changes with altitude, snow conditions, temp. etc.. As for the clutches.
You are right it should climb with a faster track speed. The factory primary clutch works fine; follow the factory weight and spring recomendations; I think 66 to 69 gram weights. The motor should turn at 7200-7400 rpm, and it should stay at the same rpm even as you are climbing a long and steep hill. It is time to replace the primary spring, they get weak over time and you loose alot of performance as they weaken. Be sure to check the primary clutch for any wear on the components.
I ran a Team clutch for 3 years on a 2003 MC 800 EFI and it worked great; they are much easier to adjust. I use a 52/42 helix and the stiffest Team spring I could buy. I don't remember what that spring tension was. Make sure the belt tension is correct. Anyway, it really climbed well the track speed 35-38 mph. This year I bought a 2007 M1000 but I kept the Team clutch when I traded the sled in. While riding in the Snowy Mountian Range this year a riding partner was a little unhappy with his 2004 MC, 900cc, efi, 162 track (Skidoo 16" wide) he just couldn't keep up with the M1000 and we noticed that his rpm was falling as he would climb the hills. I offered to let him use that Team clutch I had saved. He hadn't made 3 climbs with the clutch change and he was smiling ear to ear and offered to by it from me. I sold it. For the rest of the day he climbed right next to the M1000.
If you go with the factory secondary clutch they are alright but replace the spring with a green spring or something stiffer.
Good Luck