I was just checking out the pump selection over at...

I was just checking out the pump selection over at OutdoorBoiler.com, and I have to say, they seem to have a pretty solid lineup. I noticed they mainly carry the 1/6 hp pumps, which they say are the standard size for most installations, and I think that's generally true. It's good that they also mention the smaller 1/25 hp pump, but they're clear that it's only for very specific situations, which is responsible of them.
I also appreciate that they explain why you shouldn't just use a bigger pump inside the building – that's a mistake I've seen people make before, and it just doesn't work! The "daisy-chain" configuration they recommend for getting more power is definitely the way to go.
The Grundfos pumps look like a good quality option, and it's nice that they offer them in kit form with everything you need. Overall, it seems like they've put together a selection of pumps that are reliable and well-suited for outdoor boiler applications. If you're looking for a pump for your outdoor boiler, I'd definitely recommend checking them out!