I used to... I had an Audiovox SMT5600 on Cingular and the PPC6700 on Sprint (for work).

Now I carry just one device - the 8125. It's amazing what a less buggy ROM revision will bring (plus a working speaker/speakerphone). I also put on the leaked AKU2 ROM and push mail works very well...

Still, I miss the EVDO speed (my PPC6700 went to another office mate).