First, I guarantee you that you cannot play Computer2-Medium 'all day' and raise your rating. Computer2 is rated ~1500 against the rating pool that is chess.com Live Chess for a reason: roughly 500,000 games of Blitz. You may win the occasional game - in fact, probably 1 in 3 to 1 in 4, matching the 150 to 200 point rating difference between you and it.
Secondly, it's very difficult to get a computer to play human-like chess similar to a 1500 rated player. So, Computer2 will play like a demon in some games for many moves in a row, then like a patzer in other games ... not actually the performance of the typical 1500 rated player. Indeed, Computer2 has beaten 2100+ rated players ... an extremely difficult feat for a 1500 player.
So, in the final analysis, I suspect that you would perform much like a 1300+ player against Computer2 IF you played enough games versus that engine.
On the other hand, I could be completely mistaken. 
It seems to me that the ratings for a human and machine are very much different. The ratings for a medium computer (1516, which I can beat) is much easier than having a human opponent rated 1500+. What do you think? Is there a difference?
Should they be lowered since I could play the chess.com engine all day and raise my ratings?