Doing a loop is well within the flight envelope of almost all modern (20 years) gliders. A low stress figure that is fun to fly.
BUT...you should have a verified, accurate G-meter.
AND...the greatest risk about flying aerobatics is knowing what to do when a figure is failing. Learning how to safely recover from a figure that is going bad is the true value of aeraobatic training. Most low time acro pilots I have flown with do not know what to do when they stall out at the top of a loop. They freeze at the controls while they are trying to think their way out of the situation. While they are thinking the aircraft is gaining speed VERY RAPIDLY. It takes only the blink of an eye to blow through your Vne. All of our current acro gliders have Vne around 150 knots. That gives us a large gap between the 100 knots we typically start and end a loop at and the Vne. Your glider Vne is so close to the entry/exit speed of a loop that it would be hard to give you a thumbs up on doing a loop in that aircraft.

Get acro training in an acro aircraft and be happy.