I upgraded from mac3 to fusion atleast few years back and I would say I have not been dissapointed.
I would say that mac3 was and and still is revolutionary product in mens shaving and fusion is great upgrade, It is better than other razors in all aspects, It gives you a smooth and quick shave without any cuts or bruises in no time.
The best thing is that you dont have change the blade very ofter, for me blades lasts for around 5 months so its totally worth every buck you spend on it.