Forum OpenACS Q&A: Response to OpenACS 3.2.5 relationship to current ACS version

Maybe I should ask a new question then, but...

Where should an ACS-4.x TCL trained person jump in?  I took the bootcamp in mid-April, and have installed a local ACS dev box with Oracle, AolServer and ACS on which I'm developing a few ideas.  One is already using some stuff from the ACS 4x repository like Bboard and Photo Album (tho there seems to be an upload problem keeping Photo Album from working correctly).  Now I just heard OpenACS 3.2.5 is out.  From what I understand, the main diffs between 3.x and 4.x are 1) packages and the APM, 2) ACS objects and their integration into all the packages in 4.x for permission management - something that was never quite completed in 3.x, and 3) All services are available for 3.x, 4.x TCL is missing (at least) eCommerce  and 4.x Java has, like, 3 services ported to it.

So, how much is different beteween 4.x and 3.2.x?  Can I pick it up, having done the 4.x bootcamp?  Is the only difference the package stuff?  Is it true, then, to install services from the repository or create my own services I'll be installing the stuff by hand that the APM does auto-magically?  Are the 3.x services still available?  The OpenACS install howto points to the ACS repository to find more services, but following that link only shows 4.x services, not 3.x services.

I know folks are still using 3.x so I'm not questioning its viability ( Tali was speaking on the teleconference yesterday and mentioned a large 3.x project he's working on right now), just where is the jump in point right now WRT ACS 3 or 4 using TCL (not looking at Java right now; prefer it but I just got a call from aD a few minutes ago and was told Oct for ACS 5 the fully deployed Java-based toolkit)

Thanks.
Thanks for any info.