I have not done Sault, but have done both the other two routes up. It is hard, but not impossible. We went out with about 7 riders from the club - all got up without stopping in times varying between 1 hr 40 min to just over 2 hours. None of these riders race - just average club riders. Two water bottles topped up at the bottom sufficed and then just grind away - pretty relentless with the odd easing of the slope. If as you say, you are reasonably fit, try out the Bedoin route - the classic way up. There are lots of slow riders and they give you a target to overtake, counting the scalps helps the boredom.
Remember to take a gilet or lightweight rain jacket for the fast and cool return to the valley bottom. It is actually quite cool at the top, even when the bottom is sweltering in over the over 30's C.
Tips - I took some energy gels with me and took one ever 20 mins or so. Reduce weight on your bike, do not take lots of bits and pieces in a big saddle bag; minimise your load. Warm up before you hit the slope. If you are coming from Bedoin, there is a long gradual incline which is a nice warm up, if coming from Malacene, you are straight into the climb. I know it is a personal choice, but I hung my helmet from the bars and wore a cap for the climb as I got pretty hot in a helmet.
Good luck and enjoy the day - a cracking view from the top.