Hi spijtebijt/Erik (Rosmalen), goedemiddag!
No, I will not exchange my 40D for the new 450D/XSi, the 40D is the better camera for *my* needs: faster handling/operation speed, more direct control over features, better sized/weighted/balanced for prolongued shootings, and as far as I can tell, little higher IQ due to less densely packed pixels on the sensor, plus ISO3200 available, 6.5FPS with larger buffer, even faster and more precise AF, etc, etc...
...but if I did not need those - ? more 'profesional' ? - features/assets of the 40D, and didn't have a DSLR yet (or had one of the previous generation, and wanted to upgrade from say 10D/20D/300D/350D) and was looking for a first DSLR as 'advanced hobby camera' I would be very tempted, it has a LOT to offer...
...€0.02...
Kindest regards!
Max@Home