Barry, I've been building a 33% Cap ARF since May so your ahead of me I flew my first large gasser earlier this summer also. Some differences I noticed about the giant birds.
How solid they feel/fly compared to the small glow planes.
How long it takes for the giant planes to complete a maneuver, you actually have to hold the sticks allot longer and watch the maneuver to see when to let the sticks go back to center.
How easy it is to let the plane get really high or far away without noticing it. Because these planes are so big they get real high before they start to look small.
How fast they're flying, because they're so much bigger the giant planes don't look like they're going any faster until you get down low and then you realize just how fast your flying the plane.

The only thing I would caution you on is your speed on landing. Because a giant plane is bigger and heavier and because you've got that huge prop acting like a brake, they will loose allot of speed and altitude pretty fast when you cut the throttle.