I have both on my TZ.
First, on color DMD, both LED and the LCD are a great improvement. I go LED on my B/W's mostly ,but, plenty of people favor only LCD's. Can not go wrong either way. For me the LED seems more appropriate with the older B/W games (Stern games I am a big LCD fan). I have LED on my TZ and I am very satisfied.. I do have LCD on TS and WW and like them also. Installation is very easy.
On Pinsound, I am finding it really depends on the quality of the down loads available for a particular title. TZ has two really hi quality down loads that significantly improve the game experience. Other games I have found to have hi quality down loads are IJ, BSD and STTNG. I am working with LOTR now to see if I can find one I like. Installing the boards are pretty straight forward
On TZ, I would go first with sound then DMD, but that is me. I am finding I am enjoying my older B/W games with both upgrades tho.