Well, I feel the same way about my 20-year old DX7. I've had it for 15 years now and I still program it and play it almost every day. It's funny 'cause I've got lots of other FM synths, but the DX7 is still my favorite. About 10 years ago, when I started loosing my eye sight (pretty much "0" nowadays, so I have to use special software to use computers and stuff) I labeled all the buttons on it with Braille (using dymo tape). I swear, it takes me about 2 minutes to make almost ANY sound on it. I know that synth inside-out. May be that's why I never got rid of it....
I never had any problems with it what so ever (no wonder 'cause it's built like a ****ing tank, really).

I also feel the same way about my MINI. That little bastard brakes all the time though. I keep it in my bedroom and often play it before going to sleep.

-ED-