The biggest thing I noticed on my 300GD with 33's was (in addition to the power robbing effects) that the braking distances were also really lengthened. Fitment of 33's was no problem, no rubbing at full compression. I had 33x9.5x15 though.
There are solutions to the braking issues in the 460 like a bigger brake booster and a few other tricks I saw on the 4x4abc website. I had already sold the 300GD by the time I ever saw these ideas.
The power of the 280GE is far in excess of the stock 300GD, but the fuel economy is not ideal.
I drive the G500 model now in which the power and braking effects of 33's are negligible. I love the 460 Gwagens though, and I feel that they operate most effectively when they are configured in a way that is close to the stock designs.