I have used their products and would recommend them but remember the shielding paint when dry can flake off or particles can be dislodged when the antenna is vibrating in high winds and they could lodge on the routerboard pcb and being conductive ???
I had to apply a sealer over the conductive paint at hand i used clear varnish. I would not use SXT for a AP and my use of them was to have them attached to a dish for a PTP link.
http://forum.mikrotik.com/t/radio-card-rx-bandwidth/45267/1