Newbie -- recommend you hesitate with beginning an upgrade cycle. The bike is basically worth what you already have invested in it. Unless something is broken or just badly doesn't fit you, more money spent is well...wasted in the big picture of things. If you happen to have a 105 set just lying around that you haven't been able to sell, then sure put it back to original and sell off the scraps. Doing so won't really improve a future selling price much though