Let's summarize the OP's decision criteria here:

- Like's current bike fit/comfort
- Dislikes stem shifters
- Has a 4 mi commute
- Likes road bikes
- Has "the itch" (no, not that kind of itch)
- wants rack
- doesn't want to sink money in current bike

Performance is pretty irrelevant here. We're talking 4 miles. Luck with traffic lights and other uncontrollable variables will have more of an effect on commuting time over that distance than the bike itself (so long as appropriate tires and gear selection exist). Unless the Dawes is over 30 lbs, I'd say any weight improvements would be minimal in the sub $1000 range.

Buying another new bike so similar to your 2.3 seems like a waste of money IMHO. If you want to try flat bars, that's fine, but if like drops you'll probably just end up missing them. I have an 80s steel road bike w/ rack and a Trek 7.2 FX with trekking bars...I only ride the Trek when I need its fenders. However, look at the 7.3 and 7.5 if you want to consider flat bars.

Are you sure that's a 7 speed freewheel and not a 7 speed cassette? If it is in fact a 7 speed cassette, here's what I would do: buy a set of Ultegra 8 speed bar end shifters on Ebay and an 8 speed cassette (both cheap). Even if it is a freewheel, I'm pretty sure the 8 speed shifter will still work with the 7 speed freewheel. This way, you get better shifters in a less awkward position, and keep your bike that you already find comfortable. Want to do something else still? Put on a good set of tires...say Conti Gatorskin 700x25 folding (puncture resistant and very light). I don't think a 1.2/Allez Sport/Roubaix is going to be any faster than your Dawes with quality tires. Still want some other bling? I bought a used 105 rear derailleur of Ebay for $26. You could also upgrade your crankset (presuming its square taper), with a new Sugino or anything square taper of Ebay (again, cheap). Use your coupons for accessories and clothes. If you really want to get a new road bike from that shop, I'd get the 1.5 and use P-clips (I use them, they're fine). Why bother with Sora? It doesn't sound like it's up your alley, but a quality 80s road bike makes and excellent commuter. OK...I'm done