My, there is a very high percentage of decidedly well expressed and valid advice in this thread, and I agree with much of it.
Let me add one additional perspective.
I don’t know weather you do now, or ever plan to do your own wrenching but either way here is a point as yet un-spoken in this thread.
From a mechanics point of view I would much rather do a tune-up or a component replacement on a higher end bike than on a lower end bike because the higher end bike has a better groupo. Where adjusting the brakes so that they function (in my opinion) properly on an entry level bike may not even be possible or at least very time consuming, the same adjustment is simple more precise and longer lasting on the better components. The cost is lower also because I didn’t have to throw away and replace stretchy cables or inferior housing.