Micro 4/3 is a step down in sensor size
Nevertheless, they deliver exactly the same noise performance and DR as current top-of-the-line 24 Mpixel APS-C sensors (that of the a6000, d3300, d5300 etc.) Their only downside is being 16 Mpixels. However, it's definitely an advantage if you prefer less noisy images to more megapixels. This is why the GM1 was also high on my purchase list (along with the a6000 + 16-50 and the D5300 + 18-140) before, finally, deciding for the Fuji X-E1 because of the, now, very friendly prices.
and Fuji's lenses are quite expensive.
Disagreed. It's mostly(*) only with Fuji that kit lens aren't garbage. Actually, the Sony 16-70 f/4 can't really hold a candle to the significantly cheaper and brighter (starting at f/2.8, ending at f/4) 18-55 Fuji kit lens. Heck, even the super-cheap Fuji 50-230 (also available via double-kits) is significantly better than anything in its price range for any other DSLR / MILC.
Sure, some of their primes (particularly the absolutely excellent 35mm f/1.4 or the brand new 10-24) are indeed pretty expensive. WRT the 10-24, it's so expensive I'll go for the Sigma 8-16 instead with the Nikon mount - for almost half the price. As it's a UWA lens w/o OIS, the lack of AF / OIS support on an X systems body isn't that big a problem. (With a long lens with OIS, this wouldn't be the case, naturally.)
*: the Pana 12-32 (coming only with the GM1) and the Nikon 18-140 (kitted with the otherwise too excellent D5300) are also excellent. So are - WRT cameras vastly over $1000 - the Oly kits with the 12-40 f/2.8 Pro or any Pana high-end kits with the 12-35.