I don't have any direct experience with either board (but will be able to check out the LS9 soon when we rent one), but I will
relay information to you that I have seen in an overwhelming number of reviews. This opinion is found on the
Mackie forums, some sound forums, review pages on retailer's websites,
etc. I found it to be overwhelming.
Basically, they all say that the TT24 is a
bit slow to respond at times, but the LS9 isn't. The TT24 is much easier to learn than the LS9, but the LS9 provides a better featureset. However, there is still a tradeoff of features between the two boards, the TT24 has some that the LS9 doesn't, and vice versa.
I would look mainly to
Yamaha's
track record in the pro audio world to say that I'd go with the LS9 here. Their support is absolutely 24/7, and each support person has the same model of
console that you are using in front of them, and they try to recreate the problem then and there, and they try to help you that way. From what the
Yamaha guy said when he stopped by here, some of the support reps even have a
console sitting at their
desk in their house so that they can work from home.
The LS9 also has a slightly bigger touch
screen, and from the video demos that I went through of both, the LS9 is also easier to navigate once you get used to it.
So you can see where my vote is here: LS9 all the way!
We're actually looking at getting a 32
channel model with 2 of the 8x
balanced line input cards as a major upgrade to our sound
system. It would be used to mix from the balcony for musicals, which we are probably going to be having alot more of.