EDIT: Tim should I change the AHEADLENGTH in the NebulaReverb-TPetherick.xml I'm using for your presets? It is set to 1375 in mine right now...Thanks!
ahead length in master page does not need to be a exact number.But for this I usually leave mine at 2.0ms , this will cover the internal ahead settings I set for these presets. If it is 1375 (1.4ms in master page?) it will still be fine.
One thing I will say to avoid is if you do a extreme ahead mod it will change things in a negative way, even if my internal settings are not using this mod it seems to change things!. I don't know why it does this. Just leave nebula stock, normally you can adjust nebula ahead in master page which I believe is between 0 and 6.0ms master page(0-6000 Xml)
Keep buffer to 512 or above, 512 is best for this library. Going lower will cause the attack to be missed.