Paul -
1) Please understand I'm an Inventor convert. I was hardcore AutoCAD from the mid-80's, but since I found IV beginning with v10.... I've completely converted. I now use ACAD only to open drawings from clients.
2) That doesn't mean I don't look back longingly at some things I used to be able to do very easily in ACAD/ProPipe & CadPipe. Yes, the IV parts library is very limited. In addition, there seem to be far more constraints on pipe runs (initial fitting placement, branch connections, line size changes, etc) in IV. It's got some very nice features, but I find it more practical for running instrument tubing than doing plant layout. Much of our work is probably better done in CadWorx, but there are only so many tools you can maintain proficiency at
Maybe some day. But then again, maybe someday, plant-level piping design will be better in IV.
3) I'm still wrestling with a lot of IV piping challenges, learning every day. I have 2009 on a prototype machine, but not in production yet. One of my obstacles has always been pitched piping. IV 2009 now incorporates this, but as I said.... I haven't really put it to use yet.
4) Regarding ISOGEN output. I too have this need... and have had a MISERABLE time trying to get any info on standalone ISOGEN licensing. Tried a couple of resellers, and Alias and Bentley. All I want to find is a stand-alone license, but it seems like you can only get it as OEM bundled with something else. <shrug> Sorry, can't help you there.
Cheers -
Todd