Have put them on a Yamaha BB415 (with P+J pickups). After some woodchopping I mounted them on 5cm and 15cm from the bridge. This 1:3 distance I've calculated to be the best to get all overtones in a nice balance. I play with fingers; jazz, funk/soul and some pop; some slapping. Neck sec sounds fat and bright; very usable. Bridge sec needs some equalizing in lows. However, Br + Nk and in particular Br + 50% Nk give a great balanced sound on all strings. Br + Nk with tone full open give a nice fat+snappy sound for slapping. Compared to the original pu's the sound is deeper and much brighter, but I miss some growl. With an equalizer on 250Hz (1 octave) it is OK. The brightness tends to be too much. My strings are more than half a year old and it still needs the tone control at half. I use a Hartke HD75 with a warm sound, which works fine with the J5's. But with a bright amp+speaker it might get too much.
Installation was pretty easy, however I am not very pleased with the configuration options. See the J5-instructions at the EMG-website. There are 4 setup-configurations: (1) Passive with 2x volume; (2) Active with a balance control (not supplied; $79?) with 1x volume; (3) Active with pu-switch (not supplied) and 1x volume; (4) Active with pu-switch (not supplied) and 2x volume. At all 4 there is also a tone-control. With the supplied components only '1' can be made. When having a switch '3' and '4' are possible. '2' (which I preferred) needs an additional control (for which I asked EMG, without answer upto now). For using a switch you need some soldering. The volume controls have the most effect in de last quarter of the turning range. Not optimal. The tone-control works fine, upto a dark reggae sound.
The end result is better than what I had, but all together not ultimately satisfied because of the controls and the lack of growl. Maybe the Yamaha (wood) itself gives already a bright sound and/or the original pu's were not so bad at all. And I still want to have a balance control.