Whether to upgrade mics it depends on what you want to improve and what you like. I am recording very little, but I see that my assessment of recordings is changing. I perceive slowly more and more aspects that I was not aware of before. I think the best is to record, listen to other recordings and compare (there are many recordings on LMA). After, it is easy to decide whether you want to upgrade or not.
Schoeps actives is dream setup. Dpa are also great mics. If you are taping occasional you can try cheaper gear too. Sometimes it may also be better to learn with cheaper rig how to handle it. Any mistake doesn't hurt so much. A lot of people including me are using Chris Church's mics or Audio technica electrets as starter. When you decide to upgrade your iphone rig you also need to get a preamp and recorder (or recorder and battery box). You can find a lot of information about mics, preamps and recorders here in the taperssection.