I have both.  Some non-audio considerations: 1. in my opinion, the build quality on the M50s is overall better.  My Beats have already been back to Monster for a warranty replacement (to be fair, the process was painless) 2.  the M50s give you more flexibility in playing with various amp...

I have both. In my opinion, the MTPC is easier to get a good fit / seal and is easier to handle in situations where I have to remove and re-insert them frequently (like at work). But in cases where I can really settle in for extended listening, then I go for the TF10s. Of course, it took a lot...

I don't have any experience on the two IEM's you mention.  I'm sure others will chime in.    Note - new DiddyBeats were recently available from Amazon on a Gold Box special for less than the Monster Outlet price   I have purchased from the Monster Outlet store before - both experiences...

The Monster Outlet store has refurbished Turbine Pro Coppers for $99 + $6 shipping.   http://www.monstercable.com/outletstore/linelist.asp  

In my opinion, when it comes to isolation and IEMs, its all about the fit.  And thats going to vary from person to person based on ear canal size and geometry.  For me personally, when I absolutely positively have to have isolation, I turn to my triple flange ER6i's or my Monster Turbines with...

If you're interested in the Super.fi 3's, you can also look at the Altec Lansing UHP336's. The conventional wisdom here is that the UHP336's are slightly modified (vented to enhance bass) Super.fi 3's. If you search carefully, you can find UHP336's for < $50 Buy.com has them today for $39.99...