Not to throw another log on the fire, but the lifting/power meter/interval training for non professional athletes really comes down to the question of why we ride and how do we choose to use our leisure time. I don't have any illusion that time spent lifting is better than time spent riding, if the only measure of success is going to be who crosses the finish line first. But lifting is an incredibly efficient tool to look better, feel better, and compete against yourself. In other words, it gives its own unique pleasure and benefit beyond how it improves riding. Likewise, a power meter can enhance your riding experience depending upon what you want out of riding.
There ar huge benefits in cross training aside from what could be reproducible among completitive athletes for a specific study period. At 40, being able to roll out the driveway and do a group century, beating my buddies up the hill, finishing strong in a group ride is all fun. But I also like knowing that I can still bench 225, chin 20 reps, and squat twice my weight, and look good in a bathing suit, as superficial as those accomplishments may be. Subjectively, one is no better than the other, it just depends upon what you want. I also like being able to just throw a pair of running shoes in the back of my car and know that I can work out if I can grab 40 minutes during the day. If I break 40 minutes in a 10k charity race, then I am happy. I know that if I ran according to a strict program, I would see vast improvements, but then I would have to give something else up. And this is putting aside the fact that I coach wrestling and like to still jump in for some round robbins with the college studs. My old wrestling coach would tell me that all the running, cycling, and even lifting isn't as productive as being on the mat.
If you want to be the best cyclist possible, then it may make sense to become more one dimensional mimic the latest training of the pros and do only a minimal amount of cross training, whether it is lifting or running. But in the long run, there is a price. There are a lot of great roads and trails to run, and things to do with leisure time.
This is a great forum, but I see Lance jogging, chasing skirt, and even pumping iron with some of the Hollywood set. Even the most elite have to catch up on what they missed by adopting a fairly one dimensional program. We need more discussions of just how much fun it is to get up in the morning, have the world all to your own, and ride a bike at 20+ mph through rolling hills with leaves falling. You might want to ignore the old PM or HRM or program when all is right with the world. You feel like a kid and feel special as hell. I wouldn't trade that for all the medals and trophies that are gathering dust in my house.
I am not going to debate the science. But from a fun perspective, cross training is a hoot and keeps you in the game for the long haul.