I’ve never heard Thermarest pads being referred to as “tall” but as small or regular or large etc. I might be wrong though as it’s hard to keep up with Thermarest’s info and near constant name changes.
First there was the plain old NeoAir, then the NeoAir All Season and XTherm and XLite and NeoAir Trekker and NeoAir Venture WV and NeoAir Camper and NeoAir Voyager and NeoAir Dream etc.
Most ULers here probably prefer the shortest pad possible and use clothing or gear to support their legs for comfort and cold.
I prefer the large version in all my Thermarests because I like the 25 inch width, and these only come in size large for their backpacking versions.