I'm going to own both. So yeah. I owned STTNG, sold it, bought it back. I've played three METs on location in my area, 2 Pro, 1 premium. The premium had very little issues with the hammer and coffin lock, so I don't know what all the stink is about, but I have no doubt it's real.
Coffin lock is a very cool gimmick....but short of the multiball starting from balls getting kicked out of the scoop (YAY ADDITIONAL PF WEAR POINT!), there's no other play difference from the pro!
Honestly, wait for the met code update, unless you have a great line on a cheap STTNG that's time-limited. Owning a STTNG, and having played 4 ST Pros, and 2 LE's at this point, I'm gonna say that while the modes are more complicated, the shots really...aren't..all that different. The big difference is on the extreme sides of the playfield...under the flipper on the right and the lock on the left. The vengeance is more fun than the Borg ship the vast majority of the time, because you don't ALWAYS play Borg Multiball on STTNG, particularly if you're trying to get Final Frontier, and even when you do, probably a large amount of the time you will not have locked a ball in the borg ship, or get a ball into it for the 3x Jackpot during Borg Multiball...which means it's just decoration.
I think Met would be a better choice for you because of variety of games in a small collection, but if you're not 100% sure, then yeah. Wait for the code update, then make a decision between it and STTNG.