Don T,
Most likely the blades you've seen with dual cylinders were set up that way because the mounting geometry caused a single cylinder to have a mechanical disadvantage at one end of stroke and they used two opposing cylinders to correct the problem. IMO, you're better off designing it correctly from the start and using a single cylinder. Adding the second cylinder means adding 2 Tees and at least 2 more hoses. That's a net of at least 4 more connections to leak.
Assuming that by two smaller cylinders you mean 2 cylinders with the half the cross-sectional area (not to be confused with half the bore diameter) and the same stroke as the one cylinder, or 2 cylinders with the same bore and half the stroke of the one, you won't see an increase in speed because the total displaced volume is the same.
I would question the wisdom in trying to make the angle move fast. You don't want it to take all day, but how often are you really changing the angle? That blade out front is heavy, and the frame that's mounted to is relatively small. If you start swinging the blade too fast you going to start seeing wear in all the pivot and mounting points because of the reaction forces involved in starting and stopping all that mass.
It's always better to be smooth than fast.
Jerry