Thanks John for your input.
Well, the thing is that the Waves EQ seems to have a feature which allows you to specify how steep you want your EQ curve whereas the one in 8.5 doesn't. Also it has some vintage settings which apparently do make a difference, again unlike the standard EQ in 8.5. According to others, they say it's a gem!
Then there's the multitap delay which I can't seem to achieve a decent multitap with the Sonitus delay in Sonar (or one that sounds just like my hardware anyway)! The Waves one appears to have the settings I need but without trying, I can't know for sure and I've also not seen any posts about it, hence my questions.
As for the compressors, obviously 8.5 Pro came with a great vocal and drum compressor but I'm not convinced by the Sonitus one for general usage. The Waves one (according to others) for the vocal and general compressor work really well and you can achieve fantastic results quickly without too much fiddling. Compressors aren't my strongest area I will admit!
How do you find they compare to what's in the box with Sonar?