Go right for the weak spots first so I know what I am dealing with instead of finding out later. Open up the browser and go to hulu and veoh then some other video sites. Use that weave addon to put all my sites from my pc on it then surf around with my att sim card on edge and see if that will be acceptable speed. If it is too slow for my comfort I will then try bluetooth linking it to my N95 with the att sim card in it. If I can't get it to link then i will go find my copy of joikuspot program load it onto the N95 and then run it and connect over wifi to att 3g. Then I guess I'll be back to carrying 2 devices.
Next load 10gb of music with album art and see if it will play and show all of that correctly. Next side by side volume of speakers comparison with my N95 8gb while playing videos in the browser. Skyfire browser on N95 versus both browsers on N900.
Check out the "top row of the keyboard is too close to the screen" criticism.
Check gps performance on both ovi maps and then google in the browser.
Close every task i can then record 2 minutes of video and play it back to see if it is choppy then same thing with tv out.

If it passes all of those tests with thumbs up, I'll do the f'n nerd dance too.
Then I'll probably think of some more tests.