Right after opening, the app store seemed flooded with programs that had UIs that clearly showed their iOS heritage. And I've yet to see a singly one where this actually is good (no, Twitter for Mac isn't one). Going further along this road doesn't seem like a good idea to me. Yes, you'll save some time. But unless you're making a throwaway, gimmicky application, you'd better invest some time in creating a new GUI that'll better integrate into the desktop. This time, most likely you're not the only thing on the screen.
The decision to spend considerable time to even test the Mac market is a huge barrier to entry. This would be a good stepping stone to prove that there is an audience there.
Providing a poor quality application doesn't necessarily tell you anything about the audience a proper port would have, it can be significantly damaging to your brand, and is a waste of press attention.
Doesn't necessarily tell you anything. But it can. If you can find for 4-5k that "Yeah, people will buy stuff on mac like our iOS stuff, pull out the whole hog" it makes an excellent business case.
Also, not everything is brand based. For many things, removing the old thing from the store completely obliterates all mention ever made of it (as it wasn't the sort of thing that gets press attention anyhow).
Not everyone is selling apps that make 6-7 figure incomes. Many people are selling multiples that rake in 4-5 and doing quite nicely with that, and with no marketing.
