Originally Posted by AngryScientist

ultegra is higher up shimanos line-up than 105. they are both excellent performers.

swapping out sora to used 105 or ultegra 8-sp stuff is a bad move IMO. the sora stuff rides very well if adjusted properly, and you'll get used to planning your shifts. save your pennies until you can afford a new bike, or to take the whole group to current 10-speed.