Remember that in addition to a high FTP you want to accumulate a reasonably high training load(CTL). Even if a L4+/L5 focus resulted in faster FTP development it would be very difficult to build much CTL on a program like that. It's also tougher mentally and a lot of times burnout is as much mental as physical.[\QUOTE]
I have been told by others that as a MTBer my FTP/interval work is far more important than my CTL, given that MTB racing is characterized by very short bursts of acceleration and shorter miles, usually 18 max for expert in regional races. However, I feel that CTL has allowed me to do FTP work and still feel as if I can go another 30-40 miles. I guess that's the idea of being fit. It really is very rewarding being able to push yourself to the max and recover shortly thereafter, returning to your day without feeling as if you have just ridden that hard.
In any event, thanks for your time, Dave. I am learning. Your imput is greatly appreciated.