The utility SK tools has a benchmarking program and the Graphite kills the SP5 on all counts. But in the real world, and normal use, the Graphite is the same speed, if not slower than the SP5. I suspect WM6 puts more load on the processor than WM5 on the SP5. Pocket IE seems to be very very sluggish on the Graphite. Try browsing the normal Modaco home page (not LoFi). Scroll down the page once its loaded and the scrolling slows down to a crawl as you get further down the page. No such proplem on the SP5. Its definitely faster on game emulators such as GNUBOY, but again that is not essential for a business tool!
The only plus points are;
1. Very bright, white screen which is better than the already good screen of an sp5
2. Much firmer joystick
3. WM6 appearance- the new icons and colours are very attractive
4. 3G-I've got a 3 Network Pay As You Go sim, with unlimited 3G data for £5 per month, and its reasonable fast
5. Camera is much better than SP5