I just thought I would chime in here - I am the Promethean owner who was trying out different 10" drivers in the combo, with reference to LawrenceH earlier in the thread (page 5).
I used mine with a Barefaced Midget as a mighty mini stack and found the original 10" driver was a bit close to the edge sometimes.
I ended up using a Celestion NTR10-2520D 10" Neo driver and it worked out very well - it also shaved another 5lbs off the combos already light weight. Unfortunately, I have since moved on the Midget (needed cash) and now use the Promethean with a cheap 2X10 so I still have a 500W mini rig
The original 10" driver is this one: [url="http://www.elderaudio.com/products/Loudspeakers/LowMiddle/2009/10LB075-U.html"]http://www.elderaudio.com/products/Loudspeakers/LowMiddle/2009/10LB075-U.html[/url] which seems to be the same as the current Red Sub as stated above.
I have found my original driver and it weighs around 9.5lbs so the Beyma suggested earlier (weighing 15.5lbs) seems unlikely.
Hope that helps.