With a 4x4, you can overlay the HOTS timer from StarParse which is especially good for operative healers.
you will find that not every raid groups will follow the 4x4 layout though. I would simply be prepared to run either way. Create custom views for each type of layout so that you can get the best of both if needed. If everyone in OTG wants to run 4x4 I’m ok with that. Me, I find as a raid leader running 3x2 is easier.
I’ve run many, many pugs and have several set ups for raid frames just in case. Out of all of them, the 4x4 is the most efficient for me. I can locate the raid frames at the bottom of the screen where I can easily see them and my surroundings at the same time. I also have very little distance to cover when moving the mouse around to heal since I use mouse over macros. I can put a 3x2 at the bottom but it splits the raid into 2 groups of four with a gap in the middle and 2 more groups of four. It makes the entire raid frame bigger with more real estate to cover.
When you get a chance, please post a screen shot of your 3x2 setup with a full 16 man raid. I’m always open to finding better ways.