Um, one thought is that HN users are more targeted than just people hanging out on /r/programming.
I've done a lot of PPC over the years and the one thing I learned over and over again is the best ROI always comes when you inject yourself into the end of the buying cycle. What I mean is, the closer to making a purchasing decision they are, the more likely they are to buy whatever product fits what they are looking for because they've already been educated about the problem, solution, etc.
In the affiliate marketing world, this is why review sites are so darn popular for making money. People go to them when they are making a buying decision and if they click on the product link after reading the review, it drops a cookie and in many cases they will buy that same session anyway.
Price comparison or deal sites are also kind of in the same end point of the buying cycle. The person has already decided to buy a particular item, so whoever can offer the best deal or whoever has the best bonus item/service/brand is going to probably make the sale.
By being on HN, there are probably a lot more people looking for your particular solution than just the average reddit reading programmer. There is some overlap, but I would imagine the average HN user is closer to a devops role than the average reddit programmer. If only cuz I'd imagine a lot of reddit programming readers are working on some enterprise software where they aren't allowed to touch the DNS anyway.
Also, good job on making a follow up post that did make it on HN. When life gives you lemons...