JBL 3678-LF network question

I am thinking about purchasing three 3678's as LCR in a home cinema. In the future, I would like to upgrade the horn to SAM1HF's but I am not sure if the LF-section allows that:

http://www.jblproservice.com/pdf/The...ies/3678LF.pdf

As I read it, it is not possible to bypass the internal x-over of the box? Is this correct? Would it be a problem to replace the network with "standard" speakers connectors and use an active x-over solution instead? Are the screws which connects the network to the enclosure "available" and easy to screw out?

No inputs?

How would you compare the performance of the 3678-LF to the SAM2LF?