i have also found that the volume on my hbh-660 has gone up some after the update. didn't need it at all, but it is always nice to have the extra headroom for really noisy environments.
i have found that the best way to adjust the volume is by lowering the volume all the way while NOT in a call. this adjusts the headset volume seperately from the BB volume. then once in a call i can adjust the volume further to find the optimal setting.
if anyone is looking for a good headset for the 7520 i highly recommend the hbh-660 with a jabra eargel. i have used many headsets and so far this combination is the best. really comfortable and very loud when needed.