I use both the Avatar gel, (size 155) and the Jett (also 155). They fit the same, in that nothing hits my thighs or feels differently. The Jett is significantly lighter, so for fast rides, I use it, although I've used it for weeklong tours and centuries. The Avatar has more cush and is quite comfy too, but heavier. I'm doing a long endurance ride this weekend and I'm bringing both. (Will be doing loops late in teh ride, so I can head to my car for gear swaps.)
For 3 days, I get to part of a thousand other journeys.