I've tried the Zend Studio many times over the past couple of years I have been into PHP...
I've never fallen in love with it... and have always turned back to a standard text editor that I've used for a while now.
With the time and effort I've had to set up the Zend stuff on a windows system, and get MySQL running, etc., it has ended up being faster for me still to just edit, upload, refresh, edit, upload, refresh... :-|
I haven't tried it lately. (Zend) maybe I'll give it another shot... but the price... I haven't ever liked it nearly enough to drop $250 on it! I know feature-wise that it wins hands down, I've just never went crazy with a ton of features I never use. (IMHO

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PHP seems to still be gaining users, programmers, and worldwide recognition at an amazing pace, so maybe in the next year or so, we will see something new hit the market.... Hopefully Open Source!!!