I'm all for headroom, but let's be real, when we are talking 5k on a superwoofer, we aren't talking about "music playback" anymore in it's normal definition, nor are we talking about playing things with dynamic range. We are either talking about Gucci, Psyph Morrison, decaf remixes, etc or we are talking burps. On real music at normal levels we'd have heardroom using a 200 watt amp. That being said I'm a basshead at at heart, and yes I wil, be upping power lol
I guess my main point, which leads into yours as well is that subs dont' wake up when you throw power at them. Bigger coils are heavier, but if the sub is properly designed it will have more motor force to make up for the small increase in weight. My sub right now has a BL^2/RE right there with a TC 5200. It's 96db/1w/1m and uses a 6inch coil. Clearly you can have a big coil and have high effeciency, the two generally go hand in hand. I think when car audio manufacturers started doing 4inch coils they were skimping on the motor or something, giving them a bad name for car audio guys used to 3inch coils.