Hi all, 

Thanks again to everyone who commented on this. I've been back from the field for a week or so, just catching up on things. Here are my thoughts on the Micro for anyone considering them.

Pros

- Durability/waterproofing. One literally ended up underwater for 2 days after a rapid flood event, and it was still working. No fish or dolphin recordings, sadly, but it worked for the rest of the season - good to know! No humidity issues either, I used two of the small desiccant packets per recorder, and changed them each time I changed the batteries. I haven't used the SM Mini, but I would imagine that having the foam mic windscreen might actually be a disadvantage in wet environments, as it surely gets saturated easily and dries slowly, potentially changing the mic's sensitivity. No foam or external components = fewer 

- Usability. This isn't specific to the Micro, but the app is great. For anyone who hasn't used Wildlife Acoustics before, it's a definite plus. Love the flexibility to have multiple schedules per day (e.g. full dawn chorus combined with 1-in-10 for the rest of the day). Being able to do everything, including change schedule, from a phone vs a laptop is a big plus. Admittedly I haven't checked the latest version of the AudioMoth configuration app, but last time I used it, it did not have the functionality of the SM app.

- Availability! This might be a dumb one, but good luck trying to get an AudioMoth... Even the SM Mini is currently on backorder, as are several of the other main options.

- Sound quailty. For some applications, it's perfectly fine, comparable to AudioMoth, but see main 'con' below.

Cons

- Uneven frequency response. This is a big one. As @Oliver_Metcalf pointed out, there is a strange peak in the f response at around 6kHz. It's on their website, but I had not quite appreciated how significant it is. It's a big deal IF you plan on doing soundscape analysis (e.g. acoustic indices), because it biases recordings towards the insect chorus. A lot of my recordings ended up with clipping distortion as a result of insects (cicadas, katydids) and even some frogs (sp.) This is less of an issue if you're listening for particular species, especially if it vocalises <6kHz, like most birds and frogs.

- Battery life (a). Admittedly, I should have done some more thorough testing with this one, like @jkitzes' lab. Based on a quick test and estimates, I thought the SM Micro should get ~100 hours of recording using Eneloop Pro batteries. What I actually got was around 80 hours on average, which is pretty bad, and meant that a lot more of my time was spent going to change batteries than originally planned. It was in lowland rainforest, so low temperature was not an issue. Sample rate was 32kHz. Potentially there was an issue with my battery charger, but I tested batteries and they seemed at full capacity. I don't know whether there is some incompatibility issue going on...

- Battery life (b). I also used Energizer Lithium batteries (the best ones) on a couple of deployments. Strangely, this did not dramatically improve things! I got 90-100 hours. However, when I changed the schedule for one of the recorders from '1 min on, 2 off, 24/7' to '1 min on, 0 off, 5am-6pm', that recorder lasted for 250hrs! I don't know if this was just a fluke, or if something about power cycling differences between schedule types has a big effect. It shouldn't, but that schedule got by far the longest battery life. 

Recommendations:

- Great for short-term deployments targeted at particular species (e.g. SDM ground-truthing, preliminary conservation monitoring)

- Probably better suited to temperate sites with less insect noise

- Test out different schedules to see if this really does affect battery life

- NOT good for soundscape analysis/acoustic indices 

Let me know if you have any questions/comments! Hope this is helpful to anyone thinking about these recorders.