Hi, Marla! Thank you SO much for your opionin and feedback. I was afraid I wouldn't get at least one response.
I ended up buying a Polar A5 and I LOVE IT!!!! I feel a bit different now that I monitor my workouts by the monitor instead of the talking test. And it seems more efficient somehow. I haven't yet read the DETAILS and reasoning behind the Karvonen formula in complete detail yet, but it makes sense to me to go by those limits.
Anyhow, I am going to alter the HRM's limits and see how it goes. I've been training for some road races for the Spring and want to get the most efficient workout possible.
And....THANKS for saying I am "not a fitness novice". I am by no means an expert, but I certainly consider myself an advanced exerciser.
Gayle