the green jackets used the Baker Rifled musket, along with their 24" sword bayonet. but this was still a muzzle loader but with a rifled barrel which meant that although it was far more accurate over much longer distances than a smoothbore musket it did take longer to load because of the rifelling in the barrel.(which made it harder to ram home the charge)
The Baker Rifle with sword bayonet.
Standard issue. British Land Pattern Musket (Brown Bess)
The Furguson rifle
All 3 side by side (size comparison)
where as the furguson rifle was a breach loader.
which made it much easier and quicker to load, so the advantage of the Furguson would be in the speed of loading and the rate of fire.
obviously these troops would be more expensive to equip and to retrain.