AR combo question

I was going back and forth b/w a WOO and adjustable rig.  I am now going to go with AR combo and am leaning towards the combo with the R&B that includes the oval stone b/c I do a lot of ribs and it would be nice to have something to protect the ends of the ribs.  I would appreciate comments from people who have the AR with the R&B option. 

This would mean I would not get the combo with the spider.  Is the spider primarly for searing steaks?

Also, I have talked myself into spending $150 for the AR combo instead of $50 for the Woo.  I really don't want to spend another $60 for the rig extender w crossbar and sliding DGrid combo. Does this just give you one more height you can put it at? Will I be happy with the functionality of just the AR rig combo?