When I'm ascending SRT I use a handled ascender attached to my center D rings with a loop runner, a Mini- Traxion attached directly to my center D rings and my Petzl Pantin on my right ankle. The two ascenders back up each other, if one slips I have the other to keep me from descending. The Pantin does not count as a support device.
For shorter ascents I just tie in at the ground with lifeline and friction hitch. I use the Pantin on the tail of my lifeline to assist my ascent and sometimes add the handled ascender.
There are many options for mechanical assist when ascending. Just make sure you have two separate and independant support systems when using mechanical ascenders. I trust my friction hitch by itself, but I want double security when using ascenders.