Hi Drood,
I kept my 3 rulebooks because I like to have them for the scenarios (better balanced than later versions of the same ones IMO) and the hobby pictures/inspiration it gives.
When I got back into the hobby I wasn't expecting to get into the tournament side of things, however it is a lot more fun and not difficult at all to get into than I thought at the time. So i went and bought all the old sourcebooks on ebay and the BRB because I didn't want to pay retail for the newer books. It ended up costing more, and then I got the new stuff
The BRB is missing a lot of profiles that are very common in the hobby these days, and I'm talking about good and fun units to use - there isn't anything OP in the newer stuff. So you would have to get all the old sourcebooks to get those profiles and like I said it would end up costing you more than getting the new stuff in addition to the minor changes to some profiles/armies.
I would recommend going on ebay for the EFGT starter set or at the very least, the mini rulebook. Then it's up to you to make a decision about getting the sourcebooks or waiting to see if GW produces something else. I'd get the sourcebooks for your armies so you can play in the time being.