Modem (wifi dreampi) vs "not bba" (wifi bridge) ping comparisons:
Used a laptop with PC quake to measure against too, which was also connected by WIFI and was hosting the local server. The PC client also handilily reports ping for each connected player numerically, rather than a green bar:
First test, laptop hosting a local server, so all on my local LAN
PC = 0ms (surprisingly enough
Dreamcast via modem/dreampi = 130ms
Dreamcast via "not bba" = 0ms
Second test, connecting to "Test FFA DM" server, presumably close to me geographically
PC = 61ms
Dreamcast via modem/dreampi = 185ms
Dreamcast via "not bba" = 60ms
Final test, connecting to "Dreamcast Talk CTF", which is on the other side of the Atlantic from me
PC = 110ms
Dreamcast via modem/dreampi = 248ms
Dreamcast via "not bba" = 110ms
So basically it's as fast as a PC connection would be - nice.
So if playing against our American friends on American servers in the middle of the night (for us Europeans) you'd expect to be getting about 110 ms, so it would level the playing field somewhat against dreampi players over that side of the pond... (against BBA players.... well not so much, but not too bad).
All in all very happy with the result