This card is bugged in combination with Metalmorph. Had my Sparkman equipped with Metalmorph while Skyscrapper was in field, attacked FH Dyna, it went only to 3150.
In another instance, I attacked with my monster opponent's Neo Spacian, Skyscapper activated boost, then opponent activated Mirror Wall, and only then I activated my Metalmorph. It didn't give me the attack points it was supposed to. And I am pretty sure it should work the way I planned.
Problem is, that Metalmorph automatically add the bonus to it and therefore it can't get the benefit from Skyscrapper too. That mean any atk increases can't be done if you want to use this field spell(except the ATK after is still less than the opponent's monster one).