We ride what we sell, that way we can ensure we only sell the best. Here's Barry on the Haute Route Stelvio putting the Bespoke Base Layer through it's paces. This is prime baselayer territory - wicking away sweat on the long, hot climbs, and an extra layer of wind protection (without the need to faff about with gilets) on the fast descents.
Base layers are designed to be form fitting in order to do their job. They should be snug without being constrictive. The material has a good amount of stretch built-in, so there's no need to go up a size.
Bespoke Base Layers are true to size, and generally you should find that sizes are in line with your usual jersey sizing.