You will probably get all the X1 expanded functionality with the next version of Sonar anyway. I think that is why they are practically giving it away at various intervals at the moment- they want as few people as possible to get it for free at the next upgrade so the people who already bought in don't get too upset.
I drunk the Fabfilter KoolAid (got the whole lot)- but only really only use 3 of them on a daily basis- and two of those pro L and Pro Q can be covered by Ozone plugs. They sure do look pretty though.