After coming from an IS200, to a GS450H i couldnt agree.
The power of the GS450H i amazing, and its so linenar - it keeps pulling and there is no slow down in speed.
I got a GS450H on a 24H test drive, why not do the same with a GS300 & GS450H?
Also, i got mine from Lexus Carilse - if your looking for a new / used, give them a try and they should sort you out