I have extensive experience with both Naim and Exposure, having owned both.
I have owned Exposure amps for over 20 years, including every preamp and just about every power amp - the 17, 21 and 14/9 preamps, and from the current series, the 3010s2 and MCX preamps. I have the 4DR and 16 Mono power amps, and a 3010s2 stereo power amp from the current series. I also have the Exposure 2010s2 DAC (two of them, in fact) and an Exposure 26 phono stage (identical to the current 3010s2 phono stage).
Some time ago I had a full Naim system of 52, Supercap, 250, CDS2/XPS and Prefix/Supercap. More recently I have owned a Supernait 2/Hicap DR, ND5 XS and Naim DAC, and currently own a Superline/Supercap (non-DR), as well as a 72 and olive 250. I also recently spent a couple of weeks with a 252 preamp.
In summary, Exposure craps all over Naim from a great height at every level. Exposure gear consistently sounds better and more musical than its Naim equivalent, at a fraction of the price, with fewer boxes and less complication.
Of the current Naim series, the Supernait 2, Naim DAC and 252 were all disappointing, particularly at their prices. I thought they all sounded pretty ordinary.
The Exposure MCX is a much better preamp than the Naim 252. The 3010s2 preamp is less refined than the 252, but more musical. The 3010s2 pre/power amps (which I understand sound very similar to the 3010s2 integrated) sound much better and more musical than the Supernait 2/Hicap DR, which sounded thin and sterile by comparison.
The Exposure DAC is, again, more engaging than the rather bland sounding Naim DAC, and doesn't need a massively expensive external power supply to sound adequate.
In broad terms, the Naim equipment is consistently leaner, colder, and tonally duller than Exposure equivalents. Exposure gear loses nothing in dynamics, but is richer, fuller and more engaging.
The only current Naim kit which I rate is the Superline, which is possibly the best product they have ever made. When partnered with a Supercap, it is amongst the best phono stages available, and handily beats the Exposure phono stages. The only qualified exception to this is the internal phono stage of the MCX preamp, which is very similar and perhaps 95% as good (at a tiny fraction of the price) with the qualifications that of course you need to own the MCX preamp to use it and it has only a single loading and gain option of 470 ohms.