Bind 8.4.6 and Bind 9.4.2 are available as precompiled packages for Solaris 8, 9, and 10.
I run Solaris 9(SunOS 5.9). I used to run Solaris 7. I wouldn't miss much going back to 7 if I had to. 9 and 10 can be had for free from Sun. I haven't bothered with 10 just because I didn't see the point in migrating all my Sparc's, and I'm sure you lose more disk space with 10.
Sun hardware is top notch. (We have C= to thank for that!)
Solaris is a whole different animalix if you're used to Linux, but I really do prefer Solaris. The only *real* difference is the amount of precompiled/preconfigured software. There is far more for Linux, but it's nice to just go to
www.sunfreeware.com and install a package, and that's it.
Keep in mind you can run Linux on Sparc too.