I have all of the top bracing installed. Haven't put the bridge plate on yet,
I "tuck" all the tone bars into the X brace. The ends of the tone bars are notched into the X brace. This makes the bracing system one unit. Transfers vibration better, theoretically.
I forget when Martin stopped doing this but it was probably in the 40's. Not too many builders go to the trouble of doing this. I believe in it.
I use sound hole braces between the X braces and the big #1 brace. Martin uses just a thin piece of flat spruce to reinforce the sound hole.
I believe putting a little brace here instead can help prevent possible neck resets in the future. As this is the area that "caves in" under the pressure of the strings. It's worked so far.
I used hot hide glue on all the bracing. Which also transfers vibration better. The top sounds really good when tapped and I haven't fine tuned the bracing yet. I'm very happy with it.