I can only afford 1 icebreaker base layer so far. However, I find it not very tight fitting like heattech. Icebreaker cutting is more like T-shirt. Some air pocket in my body.
I bought my very first Ice Breaker approximately 17 years ago in a small shop in NZ, its a black 260 base layer, half zip, the knit is so tight. Then I bought another same one about 7 years later, although both are exactly the same, half zip 260, long sleeves, however, the first one weight heavier than the later one, and it was Made in New Zealand, a true NZ merino wool product. Since then, I purchased more IB, but none of them are Made In NZ.