This is without a doubt the best (one of these types of things) I’ve used. Built-in systems are usually rubbish anyway, and you’re really committing to them – massive holes in your guitar and whatnot. I loved the first TWA, but it had plenty of downsides. I stuck a slim power bank to mine and hardwired it into the battery terminals, which fixed the power problem.
I have an arched back on my guitar, and this has really made a difference to that. It’s a great thing to play with, but it comes into its own as an inline FX processor when plugged into a PA (or amp). Hands down, the best acoustic multi-FX I’ve ever used (outside of a computer, anyway).
Also, your old bracket is the same as the new one, so save the one that comes with this for a second guitar. CLASS!