The hole to hole center distance on the taurus 52 is a tad under 4". I can't get to my stuff right now to measure, but a phone call to Bill at Taurus will give you all you can ask for. He's always ready to answer questions when they arise. You may have to try more than once to get him, but I assure you that he'll answer any question you have.

As for the plane choice, that kinda difficult to be absolutely specific about. How does one or the other fit your transportation capabilities? What do you prefer for aircraft appearance lines? Are you going to want to fly some precision? Only balls to the wall 3D? All of those questions have an impact on the selection.

For 3D only, the the new Edge would be, and is to be, MY choice. For a mix of precision and 3D then either the Yak or the Extra will be great. For a smaller vehicle then the Yak wins hands down.

The difference between the Edge and the Extra will be that the Extra will hold a straight line better and still fly lightly and accurately. The Edge will be a turn and burn airplane and will suit the needs well for all those that don't prefer the geometry of IMAC.