I'd agree, and only really use it (for cycling) if riding <100km. I do however use it for running, rowing, and lifting weights, too, and I'd never use a garmin for those.
The real question is do you even need a HRM? What are you doing with all this data you're collecting? Is it actually helping you achieve your goals? Do you really need to know how many calories you're theoretically burning from exercise, because frankly, they pale into insignificance against the calories you burn from just breathing, and there's such a huge variation between individuals you might as well make it up, they're all pretty much guesses.
Disclaimer: Me, I just love the stats.