After reading it all, it sounds like a PITA for Safari. I would do simple math: check how many users of RES for Safari are, get the 10% of them, and see how much you will have to charge them to regain USD $100.
But even so, assuming the Paying User Base grows the same “minimum” a year, it sounds like the costs of developing and maintaining it outweighs any other reasonable pro:
- You have to buy a Mac.
- You have to pay USD100
- You have to invest in time for Objective C this, constantly.
- You have to invest in time for Shitty Apple Review process.
Personally, I would kill it. That would free resources for other platforms, making the experience better.
Closing thought: Why someone would pay for RES for Safari, when for other platforms IS FREE?