have been worth cheering as a breakthrough but 
(ROOT (S (VP (VBP have) (VP (VBN been) (ADJP (JJ worth) (S (VP (VBG cheering) (PP (IN as) (NP (DT a) (NN breakthrough)))))))) (CC but)))
(ROOT (S (VP (VBP ) (VP (VBN ) (ADJP (JJ ) (S (VP (VBG ) (PP (IN ) (NP (DT ) (NN )))))))) (CC )))