Thermolite vs Merino

merino rules

synthetics take on perma stench so despite cleaning every time they are used they smell within a few minutes of being put on

the quality of the merino will also affect its performance and longevity, my endura base layer is not as nice as my rapha one, so is used less often yet has bobbled more.

the stench effect is down to your skin, its pH and the bacteria you carry, so some people are fine with synthetics

one of merinos differences to synthetics is that it will hold more water but despite holding the water it still insulates very well

you get what you pay for, buy merino if you can afford it

I think Synthetics only take on a perma-stench if you don't wash them with decent stuff, after selling all this kinda shizzle to people for nearly 4 years when I was younger, anytime I recommended someone use a decent anti-bacterial wash their base-layers stopped smelling like shit all the time, amazing eh!
Good quality merino is great, good quality synthetic material is great, but they need to be treated accordingly, and anything thats spending that much time being sweated in should be washed in a decent anti-bacterial base layer wash if you want to stay hygenic.
Also bear in mind that each material has its plus points and different uses, for instance in the height of summer, I wouldn't wear Merino Wool unless I wanted to be swimming in my own sweat and feel constantly moist, likewise in the winter I wouldn't wear just a synthetic unless I wanted to be freezing my arse off all the time.
This is why most top end base-layers, designed for heavy physical activity in extreme cold weather combine high end Merino Wool, and high end synthetic material, which as I have been saying is the superior combo over just Merino on its own under these conditions. I get by on nothing but a synthetic layer, underneath a merino layer, underneath a shell jacket, all winter long... and I stay dry and warm :)