We did the Flying Fox Helihike in early December. It was a unique experience and I'm glad to have done it. I got to sit in the front of the helicopter on the return and that was amazing! Our guide was Zorah, an Australian with a snarky sense of humor. She made sure we got to see cool things as the weather was a wee bit threatening and may have shortened our stay. Luckily, it held off and we got the full tour. She obviously loves the Glacier and what she does. Amazing caves and ice structures.
There's really no strenuous activity involved. Short walks and stopping to take photos or learn about the glacier. It was expensive and I'm glad we did it. But it's really a once in a lifetime experience.