quantifying design criteria

So I'm beginning an experiment with designing a recumbent. I'm also a
complete bent newbie but I do have some metalworking/composites
experience and a lot of upright wrenching experience so I figure it's
worth giving it a go.

Having said that I'm trying to pin down what the bent community means
when they say a bike is "fast" or "slow". I mean it's obviously
related to seat angle and BB height. a Tour easy is a differnt beast
than a bacchetta aero. But how about the different between something
like the aforementioned aero and a street machine. BROL describes the
aero as fast and the street machine as being kind of slow. But the
riding positions are similar. (particurlarly on the 26/20 version of
the aero) A quick analysis of the side pics of both bikes suggests
that with a similar seat angle the frontal area would be quite similar.
Is weight the major player in this comparision then? Or is it a more
amorphus "this bike feels fast" kind of judgement.

My goal is a high-racer/fast touring style of bike. Challenge serian
or similar. I haven't yet sold myself on teh 26 front wheel tho. I've
never ridden a bike witha seat that high and I was wondering how it
might fare in stop and go traffic. The extra visibility would be nice,
but I'm worried about getting a foot down. I have a 35 mi rt commute
of which approx 5 mi each way is in traffic with a lot of stoplights.
Thoughts?

Cheers and thanks for helping a newbie out.

-Tim