John,
I use probing for touching off "ALL" tools and use a simple tool setter. Find that it is the most accurate and repeatable of all the methods. I do not double probe the touch off but rather probe at a slow rate eliminating the over travel. I use a few macro's but the button scripting takes care of what is needed to be done.
By "ALL" tools I am meaning things like reamers, drills, whatever and a few buttons provide for any changes required. To touch off any lathe tool you need 4 surfaces / references when probing.
I use the master tool concept such that tool one is used to define all the other tools. It is not used for machining and it is just a piece of 1/2 round carbide and the sides are parrel and the face is perpendicular to the sides. Once the tool table is populated any tool can become the master tool. If tool #1 is broke and needs to be replaced then you can use say tool 10 to replace tool #1 with the proper offset.
My tool setter is home made and cheap! Simply it is a piece of ground round with a 1" micrometer standard on the end of it. The mike standard is mounted on the end of the round, centered and the flat surfaces parrel to the round.
I just put electrical tape on the round so i can probe to any of the mike standards four surfaces.
Now you say .....tape on the ground round and he is accurately finding offsets.....I hear it now...give me a break, Rich!
It matters not what is holding the tool setter, you must center it using an indicator 0.0001". The tool setter just provides a common reference X Z plane for the tool to touch off. You need that to have "0" runout in the X direction and the plane can be slightly above or below lathe center. My three jaw creates a small runout on the tool setter, so it's easy to center the setter on lathe center.
BTW, I don't use home swiches, always start by using the tool setter to find lathe X center via probing. Then manually define a home and tool change location and both are at the same location (KISS). Then define the G54 Work offset. I use a quick change and probably the most number of tools used in one machining operating was around 8 tools or so.
RICH