The Sirrus should be a little cheaper (at least they are around here). I've taken a Sirrus Sport for a test ride and a Trek 7.3fx as well. I preferred the Sirrus.

Don't ask me to quantify my response. The Sirrus just *felt* better to me. And to be honest- I lust after a whole bunch of different bikes, but the odds are when I finally get around to buying again- I'll probably end up with the Sirrus Sport simply because the LBS keeps them in stock (in my size). Bunch of other brands/models I've inquired about are either difficult to get or just plain sold out.