I agree that most tools that are similar are fairly easy to switch between: PHP/Python/Ruby/Groovy, and Java/C#/C++, all imperative, OO, etc. Also, from a tools standpoint, Rails guys can use Django and vice versa, pretty much the same, for sure.
It also sounds like you agree that that's not so easily done with (quoting myself from above), "some programming languages/tools/methodologies." So sometimes, sometimes not.
The two you mention (Haskell and Prolog) are great examples of languages where people can actually have negative impact for a while until they really get up to speed with the language. Pretty much any functional or declarative language fits that bill, and definitely any Lisp. Maybe not 6 months, but definitely at least a couple of months to start contributing a lot of additional value (in addition to getting set up with the team's environment and workflow).
Amazingly, even if someone does learn Java, Python, and C, he or she is not necessarily able to generalize that knowledge to other languages, or even to larger-scale projects in those languages. For example, I wouldn't want to take someone with a lot of Python experience and a semester's worth of C, and put them on a large-scale firmware project or Linux-kernel-hacking project. There are a lot of ways somebody who thinks they know C could mess up a project like that.
In general I agree with you: a truly smart engineer can pick things up as they go, especially on a longer time frame. However, this isn't always the case. Though my perception is admittedly warped a bit working in startups, where you need people to hit the ground running immediately.
While I agree with the general idea of the analogy (that great programmers are effective, no matter how many specific years of experience they have with language X), it doesn't quite hold up. It would really only be accurate if learning to be effective with brown/walnut/etc. could take several months, as is the case with some programming languages/tools/methodologies.
Unfortunately, scraping another site's information is generally not a long-term viable business plan (speaking from personal experience). I suppose CraigsList, much like insurance companies, doesn't like its valuable information being displayed on other websites without endorsement or consent.
That said, I love PadMapper, having used it a couple of times for finding apartments in the Bay Area. So it's a bummer that they won't be able to show CL listings anymore.
Excellent question, and I think it's something that I didn't address very well in the site/app description. The main problem I was trying to solve when designing the app was to make something that was really easy to use, while still having the features that are missing from many free apps (drag-and-drop reordering, lack of iAds). In my experience, I haven't really found any other apps out there that can say this.
That said, I think you may be right that $1.99 is more than most people are willing to pay for it just because it's easy to use, so I lowered the price to $.99 through iTunes Connect. It doesn't look like the change has been reflected in the App Store yet, though. The $1.99 was a bit of an experiment, since this is my first app.
Thanks for the feedback, and I think you're right.
I updated the site to focus a little more on the specific benefits/advantages of the app. I guess it's a little difficult to market something like this that has deliberately few features. The main reason that I love it is because of how fast and easy it is to use, as I don't even have to think when adding something to a list. Unfortunately, it's hard to communicate that via the web...
It also sounds like you agree that that's not so easily done with (quoting myself from above), "some programming languages/tools/methodologies." So sometimes, sometimes not.
So... we agree? :P