Originally Posted by
gsa103
That was a fairly comprehensive list, but I'm going to make a few changes. Mainly because Saint & Zee are in the wrong place.
I'm going to make a few qualifiers and changes.
The Saint & Zee components are designed for DH mountain biking. They're heavier and more robust than their XTR/SLX brothers.
In terms of functionality, generally things get smoother and better working up to the XT/Ultegra level, with XTR and Dura-Ace being about the latest features and lowest weight.
105/SLX/XT/Ultegra/XTR/Dura-Ace are all currently 11-speed rear systems. Below that you typically lose 1 gear per groupset tier.
I currently have bikes with everything from Alivio to Ultegra & XTR. A new Deore derailleur will out-perform an old worn XTR derailleur. Design improves and components wear. Deore/105 have excellent shifting, the shifts get marginally lighter above that. New Deore brakes will blow 3 generation old XTR brakes out of the water. There is no comparison.
The sweet-spot for price/performance is probably SLX or 105/Ultegra, these have all the features of their higher brothers but at lower cost. A lot depends on sale pricing and where you're getting stuff from.
OP is looking to replace parts on an old Trek 7200 he bought for $40 to commute a couple of miles per day in Washington DC, and would likely be parked outside exposed to the elements. It would seriously be overkill to put SLX, 105 or Ultegra components on such a bike. This bike would seem to be a candidate for maybe looking for used donor parts from a bike coop parts bin, or alternately, going with the cheapest Shimano or similar quality part available.