When we bought my wife's 520 a couple of years ago I got a quote for the basic bike. I then asked for a second quote for an LX drive train, a flat bar, LX shifters and Avid brake levers. It was the same price. as the lbs owner knew he could use or sell the original components. The price was $100 US below retail.

We have noticed no significant difference between LX and the basic Deore shifters which we had on our mountain bikes. However, the 105 front derailleur was hard for her to operate with a thumb shifter as she has some arthritis in her hands. I upgraded to an XTR and it made it much easier for her. Today I wouldn't get an XTR as Shimano has redesigned the XT and it's now a very good derailleur. The XT is actually a better match for the compact crankset (22,32,44) than the XTR. I have it on my mountain bike.

Our mountain bike Deore pods got sloppy over time with wear and she now has XT and I have XTR shifter pods. They do shift better than the basic Deore.

Unless your 100% set on flat bars, you might consider the newer ergonomic drop bars made by Ritchy. They have lots of hand positions on the flats and the drops are better shaped for the hands and shallower. You have two choices of drops. Mine have the least drop and they are very comfortable. You can also have STI shifters with drops. I could never go back to anything else for a road bike now that I've used 105 STI's.

Al