Sounds great. After reading/hearing the good results you've had with them, I've got a jjb-100 on the way to try out. Not sure what I'm going to put it in yet but most likely a baritone. If it works out alright, I'll probably pick up a couple more. Any installation tips/tricks you've learned along the way?
1) Just a dot of the thick "gel" type superglue works well to hold them in place - you have to hold for about 30 seconds to a minute but it gives you a little time to ensure the placement is good. Disposable Nitril or plastic gloves aren't a must - but I came
this close to leaving some skin behind in the first one I did.
2) Feel around inside and plan your placement and your strategy for getting the pickup in place before you put the glue on it. The KoAloha was the easiest bedause there was no fan bracing to get in the way.
3) If installing in a soprano make sure the sensor will fit. I ordered the 15mm pickups for my two sopranos - I think the 20mm would have fit but would have left fewer options for placement.
4) Placement doesn't seem critical, at least not in soprano and concert size ukes. Just watch that you don't end up actually touching a brace and that the lead won't be resting against a brace or the top because it will buzz; I initially had a minor buzz in the baritone that I tracked down to a lead just touching one brace. If in doubt you can use a thin piece of stiff cardboard to deliver a dollop of hot-melt glue to hold the leads in place against the back of the uke or what have you to keep them from moving. I ended up doing that on the baritone and then went back and "retrofit" some hot glue on the other ukes to make sure that the leads wouldn't give problems later. All the pi tures show these being placed on the bridge plate - you probably won't be able to reach the bridge plate and, frankly, I think the "sweet spot" is actually on the top just in front of the bridge plate, anyway. You might get a little more volume on the bridge plate itself, but I think you get more character of the top when the transducer is actually on the top.
5) For drilling holes, apply some painter's tape to the outside of the uke first to make it less likely to chip. Then, use the right kind of bit. I can't think of the name right now but the bits I use have a small pilot bit in the middle with the typical beveled drill tip, but the rest of the bit has no angle to the leading edge. They are designed for cutting flat-bottomed holes when making furniture and the like but they also are less likely to chip the wood because the bit doesn't angle into the wood.
Make sure the bit is sharp! Dull bits chip wood! EDIT: the step bits or Unibits are also supposed to work well, though I haven't tried them. The trouble is that most of these bits have very short lateral distances between steps - this is okay if you are drilling the side - if you are using an endpin jack the heel block and side are going to be anywhere from 3/8 to 1/2 " thick.
6,7,8,9,10) Take your time and have fun!
John