I do agree with what he has to say. Learning on a 600cc is much less forgiving than learning on a 300cc or 250cc. Full throttle a 600cc and you can easily get into a wheelie, could result in an accident if you don't know whats going on.
I agree with being able to use the higher revs and that is great fun and safer than opening up the throttle on a fast bike. If I do that in 1st gear on my Triumph Street Triple r, the front end comes up. Still, it is also fun to have a faster bike too. There is no substitute for rolling on the throttle in 2nd or 3rd gear merging onto an interstate and going from 45 mph to 85 mph in a couple of seconds, or seeing an opening and just going for it knowing you can get ahead of everything. More likely to get a ticket too. Riding a faster bike eventually makes you an even better rider. It also makes the smaller bike feel like a toy when you get on it. When I get off the Triumph and onto the Ninja, I notice how slow it feels and how short the gears are. Still, the 300 does what it does very nicely. It works fine in town and equally well on the interstate. It lacks that exhileration, or should I say it is short-lived. Really a guy needs at least a couple of bikes anyway. No, you certainly do not NEED a faster bike, but you will most likely get one cause you will love the adrenaline rush.