[daeken]

I didn't have to drill anything at all -- fit perfectly. Just make sure you print out the template first and check it. The install took me all of maybe 5 minutes; it took me longer to figure out how to calibrate it for the first setup than to actually get the thing on the guitar (protip: read the manual first ... I didn't).

I don't notice any difference whatsoever from the Hipshot locking tuners I put on there previously. However, this particular guitar is slightly insane, weight-wise; two heavy magnetic pickups with metal cases, piezo bridge and preamp, GK-3 MIDI pickup. It's chambered, but weighs more than an unchambered LP Custom, due to all the extra equipment. So the headstock doesn't exactly add much.