Welcome to the forum, personally I'm not a big fan of the ankle rig unless it's a backup option. Going to the ankle for your primary option in a self defense situation would be weird for me but YMMV. I carry a Kel-tec in an ankle rig as a backup option to my winter EDC. Definitely check out the M&P compact line as they do have the thumb safety option you are looking for.
"Regardless of whether justified of not, you will feel sad about killing another human being. It is better to be sad than to be room temperature." - Joe B Fricks.
01 FFL, GOFFA, NRA, GOA, IAVA, VFW, ABATE of Iowa D15.