not a PITA but they don't really provide a ton of instruction. just had to feel it out.
ok, so they tell you to use a squirter thing for the caps to get the air out. just open them in a 5gal bucket of water and shake the caps and you'll get every bubble of air out of the system. then you close them up and put them in the soil.
they also recommend you thoroughly water in the soil before installing the blumats... i dont believe you have to do it thoroughly, just make sure it's the moisture level that you want it to be. if you thoroughly water it in (like to the point it almost drips) that's too much moisture, and you're setting the sensor for that moisture content.
to combat the problem i mentioned above, i have been dialing back my blumat dripper so that it hasn't been watering and my soil has had a chance to dry up a little bit. they would start to drip, and i would shut them back to hold the drip of water again. when i felt like the soil was where i thought it should be at for moisture level, i let them continue to drip. IMO they are now dialed in. I did it completely by feel, i dont have a moisture meter or anything fancy like you do
I don't think you'll have a problem dialing them in if you pay attention to the things i mentioned above.