The iPhone 4S has very positive sound characteristics in my experience. I wouldn't shrug at using it to drive a top-tier earphone. However, I can't tell you if getting a high-end set as a daily beater is a "waste of money". Only you can make that decision. I will say that I have not been very careful with some of my customs just to see what would happen. I once got my Alclair Reference caught in door in a really bad way. The cable detached from both earpieces and from my mp3 player. Had to bend the cable pins back into place but other than that no permanent damage.
If you're looking to stay reasonably close to the PFE 112 sound signature without spending a whole lot the ClearTuneMonitors CTM-200 might be an option - it's about as durable as any other custom would be and offers a reasonably balanced sound slightly focused on the midrange and treble.
Thanks for responding Joker. I wasn't very clear in my post so I will attempt to clarify. I will be using my PFE 122's or the Hm RE 262's as the beater set but I was thinking about going the custom route for my nice set. I don't want to go though the trouble of a custom just to get a mid level set. I would prefer to go all the way, just from quick reading of this site and others I was thinking of the UM Miracle. It seems like it is well balanced, (the detractors just have minor complaints and it is not an item where some hate it and some love it). I personally prefer to spend the money up front and not spent the next 6 months worrying if I made the right choice and if another option would have been worth the money. Let me know if you or anyone else has some advice for me.
I have learned so much in the past 24 hours that I have been on this site. Thanks to all.