Training with a HR monitor

As you say, its a much cheaper way of measuring performance than power meters and has limitations due to this.

I use mine as a relative measure...recovery if relative to your current rate only so disregard inaccuracies due to health, time of day etc....if your riding at 170HR and you recover to 140 within 5 mins riding in a pack, youve got recovery going well for you, if not youve got work to do.
I record all my av and max HRs from all my rides over the year and even though I dont ride as often as Id like to, I can still see progress and development. I also note my general health and other factors like a normal old style journal.

G Obrees book is excellent and he doesnt discount HR monitors, he just points out their restrictions in his attention to detail. Every training manual is a guide, stick to the letter and it will assist you if your looking for that exact level of development. If your not aspiring to be at the highest level you can still take a hell of a lot from it, especially in measuring your development through your 20min max level.

In just one year, ive discovered my peak rate is 170/5. I dont get my HR over 185 often and max is usually around 195 though I know its actually more, can reach 210 if I want to train more often but not chancing it without regular training like I used to do.

I can see that my past base training levels where performed at 160+ where now its more like -150 so theres a big change for the better.

Ive also managed to increase AvSpeed V AvHR over sustained rides whilst improving recovery...all from relative HR measures so exact detail isnt a factor.

I wouldnt be without one for measuring performance based on recovery and relative effort.

Would love a Powermeter of course, but Id only be measuring it against my HR for recovery anyway....my legs tell me when im fecked!

Throwing up is a good indicator of max HR I find.

I have found that 'nearly passing out' is a reasonable means of establishing max HR

In contrast, Graeme Obree in his manual was against training with HR. Partly due to the reasons Jimmy outlines above. Where he did say it was useful was for recovery rides so that you don't go to hard on easier off.

I have not been disciplined enough to use it properly and have come to the conclusion that you should ride really hard or ride easy. Audax or timetrial/cyclocross as the base.

Training with a hr monitor is just dandy, you can do nearly all the same sessions as with a power meter almost as well.
Limitations of hr is simply that it is subjective; ie it shows your response to a work load... Power shows the work you are doing. It is better to control the load rather than the response for optimum training. Which is why power is better.
That said, you train at these loads to get a 'response' so if you know your response (heart rate) then you can rest assured you are on the right track.
Dehydration, fatigue, illness and freshness, hell even time of day can effect heart rate, so there is a bit of personal learning to be done but it's still a great tool.