Yes, I have an HTC S620, aka a non-T-Mobile, T-Mobile Dash. Unfortunately, it has the PAN profile, but not DUN. Following the guide, I am able to get my N800 talking through it and online, but I don't yet know how to make it pretty and integrated into the GUI. I have created the dummy AP, connected to it, then run a variation of the BT UP script from maemo.org (w/o the insmod bnep.ko), then when I'm done, I run the BT Disco script (w/o rmmod bnep.ko).

The other difference I've found, is that the instructions on maemo.org talk about using the dbus-s program, which doesn't seem correct for the N800. My system seems to work fine when I don't run the other scripts, just the connect and disco scripts.

And to actually answer your question, yes, Opera does work when I get everything connected.