Theoretically, the breech loader should have greater recoil, all other things (weight and design) being the same.
This would be due to the small loss of pressure from the ignition device, whether flint of percussion-cap ignition.
If there is no loss at the cap, then the recoil should be virtually identical.
With a new nipple, my 14 bore does not vent from the nipple at the shot with standard load, but still does, just a bit,
with the 6 dram hunting load. This said, it is still not enough to cause the spent cap to depart the nipple.
With original rifles or smoothbores, I would expect much more loss of pressure at the "tube" than with modern nipple designs.