Apple hardware always lags behind. I considered buying an iMac a few months ago, but when I looked at the hardware specs and the price they were charging for it....I just about choked. So I decided to build my own and was able to put together a rock solid workstation with at least 5 times the power for less than $600.00. The iMac is simply over priced....like ALL apple products.
My suggestion is to build your own and install Linux or install OSX.
I'm curious what processor you used that has 5 times the power of the i5 that the iMac uses, and also if it makes any difference for everyday tasks (Safari, Mail, iWork, etc.) other than raw video/audio encoding...
And a few more questions:
Is your computer also in a space saving and elegant all in one design?
Did you get an IPS monitor with 2560x1440 resolution (I think those run around $1,000 separately)?
If you have some sort of weird issue in the next few years (up to 3 years if you consider AppleCare) who are you going to call to have your problem diagnosed and repaired? Are you going to call the internet?
My point is you can't compare Apples to Oranges. Apple computers have a unique selling point and their value is not easily duplicated. In terms of raw power, your computer may be doing better, but Apple users are looking for the whole computing experience, which I guarantee your machine does not duplicate (and neither do OSx86 hacks), not raw power.
With that said, I too am torn between waiting and buying. Since my Aluminum 20" still gets the job done, I think I may just wait for the upgrade. Though I am sure if I get the 27" i5 from the refurb store it would be more than enough for my needs for years to come.
The biggest thing I would want though is for my computer not to have all the issues everyone talks about with this current crop, and I am a busy guy (I run a small business) and I use my computer to get work done, so I would not want to play the return/exchange game by mail (which could take weeks) or by wasting 3-4 hours a day until I get a unit that is satisfactory. It'd be different if I was unemployed or a student, but to me that would really be a hassle I'd rather not deal with.