I took a few bikes out for some test rides yesterday at the LBS. I liked the Specialized Roubaix Compact. The store has the 2013 model at list price ($1750) and a left over 2012 model at $1800 (which would be 10% off the original list for this bike). The '13 model has the Sora components while the '12 model has Tiagra. My understanding (though, please correct me if I'm mistaken) is that the frame and geometry are essentially the same from '12 to '13. Another option would be the '13 Roubaix Compact Sport, which comes with 105s but comes in at $2100, which is more than I wanted to spend. I'm leaning toward the '12 with the Tiagra components but wanted to consult the hive mind here to see if there are issues I'm not considering when comparing across model years (I'm not certain, for example, whether or how the components themselves might change from year to year). Thanks for any advice.

Buy the 2012. Even though the sora is newer I still think tiagra is better. Rode it myself and can't fault anything on it. For $50 that's definitely worth it. Check the frame spec on specialized site. If they say the same thing then the frame are basically the same.

Not sure about the particular model you are interested in from '12 to '13 Model year. I will say this as a owner of a '12 Roubaix SL3 Pro I built frameset up with Campy 10s, I am astounded by how good the bike is, and I don't impress easily. So you are in the right ballpark whichever bike you choose.
Possible the Comp is unchanged for '13 but I would opt for the '13 bike anyway. The groupset thing is pretty incidental and you may change out part of the whole thing over time anyway.
You are in for quite a treat. A great time to be in the market for a new road bike.

Btw, Specialized did redesign the Roubaix SL3 for 2013. It has been replaced by the SL4. It is a complete redesign even though the geometry is the same...every frame section shape has been changed for 2013. I have not ridden a 2013 SL4 Roubaix but a few members on the 41 own one. I have to say, I don't know how Specialized could improve the SL3 Roubaix but apparently they have.

Let us know what you think of your new bike and have fun.

I would get the 2012. I have 4600 Tiagra on my secondary bike and it shifts great but make sure the hood shape works for your hands. I don't have huge hands and the Tiagra hoods are too small for my primary bike. I find the 105 hoods much more comfortable. I tested the new 2013 Sora and wasn't impressed.

10% off is weak discount for a 2012 bike. The 2014's will be in stores in 90 days, I'd expect 20-30% off a 2012 at this point in time unless you're in a small bike market. Anyway, I'd go with the 2012 10 speed over the 2013 9 speed, and I'd also offer them $1600 out the door (ie after tax).

I was at my lbs today and they have a 12 left with tiagra and it was 1500.00 if that helps you negotiate.

Offer them $2000 tops for the 2013 with the 105 components. As noted the 2014s will be released any day now.

I purchased a 2012 Roubaix Compact Comp in May. List it was $3300, they were offering it for $2700, I got it for $2500. That's about 25% off.

Don't hesitate to negotiate.

Wait until the '14s drop. Seriously. It's a matter of days, and it'll absolutely help your bargaining position for either bike when they have a floor full of the new model year making the '12 and '13 look dated.

Also OP, if you don't want to move up to Ultegra, I suggest you get 105. I think a Compact is a good thing btw. The '12 to '13 thing maybe a jump ball for the model you are considering which maybe derivative of SL2 with FACT 8 carbon.

Why not try and get 10% off the 2013 Compact Sport, get the price down to more like $1900 and get the higher components? Make them an offer, the worst they can do is say no. If you can pay cash/check for it you save them card processing fees which would probably run somewhere between $50-75 on that purchase. Paying cash might get you a further discount if the LBS is using a commercial credit line because cash goes in the till and the owner decides how to allocate it whereas cards and checks go into the account and the bank gets first dibs on it.

Just an update for anyone who might still be interested. I found the same 2012 bike at a different LBS for $1600. Went back to the first store and ended up getting the 2012 for $1500. Feels like a decent deal to me. Brought it home today and got 17 miles in (happy Father's Day to me!). Took about 5 minutes off my previous best time for the same route and didn't even push that hard so I guess it's working for me. It's going to take some time to get used to the gearing (2x10 vs 3x8), the drops and the more squirrelly handling vs my old flat bar road bike but I'm looking forward to getting some longer rides in.

Nice Dude!