Well.... What are you looking for?
A new toy? Yes, it's worth it
A smoother marker? Depends on how you tune it
A more reliable market? No, DM7 is just as reliable to a dm9 or nt..... Depending on how you maintain them... NT has some teethig issue at the moment for some owners, but I have personally not yet have a game ruined
Are you looking at improving your game with a newer marker? If you suck with a dm7 , you will still suck with an NT... Period....
Have you tried shooting the NT and a DM9? It would tell you wether it's worth it... I first shot a 9, fell in love with it, can't afford one, so I bought a 7 instead... No regrets
Can you afford it? If yes, then it's worth it... If not, nothing wrong with sticking with your 7, as it still shoots great
or.... If you like to collect lots of markers, than yes it's worth it
at the end, it's your money dude... Don't let me or other people tell you how to spend it.