Actually I would buy a bolt on external ballast before encapsulated. For a rocky granite coast encapsulated ballast would probably be my last choice unless really well executed..
I have seen far too many encapsulated boats hit rocks and then require months of "drying out" the keel before any repairs can be made. Watched an Island Packet sit on the hard burning up an entire season before it was dry enough to repair.
On the other side I have seen external lead patched up while still in the slings and dropped back in all in the same day.
I have also seen encapsulated keels split open in the winter due to entrapped water likely from an earlier grounding and improper dry-out time... While there are some builders who did encapsulated well, such as Caliber, many do not and the dry out times after a hit can be extensive. This means an out of commission boat for a good part of the sailing season.
This was one of my customers boat with internal ballast. The internal ballast got wet, it froze and split the entire keel bed meaning more water drained into the encapsulation. Arghhhh... Note the upwardly cracked fiberglass between the bilge hoses...
For those who don't think
bolt on is robust enough this was a Hunter 340, a boat many pooh-pooh as a "production boat". Pretty darn tough, if I do say so myself....
Check out this chunk out of a lead keel below!!! That was a HARD HIT, about as hard as it gets. This boat did not sink nor lose the keel. All keel bolts were still intact despite there being only a few of them compared to some other builders in this size range and this was..
This was a FULL BORE hit to solid immovable granite. Both the keel and hull survived to sail another day. While the keel was re-set it was more to inspect and die test the bolts.
If that 4100 pound lead keel on a 11,000 pound Hunter 340, with only 5 keel bolts, can handle that, how do you suppose the 3850 pound 12 bolt keel on this 36' 8900 pound day sailor would do? It would likely move the granite!!
There are differences in quality among encapsulation built boats as well as external bolt on. Buy a well built example of either and you'll be doing well.
I don't hear anyone running away from world cruiser brands such as Morris, Passport, Hinckley, Halberg Rassy, Malo, Cape Dory, Bristol, Gozzard Yachts, Valiant, Pacific Seacraft etc. etc.. all of which use external ballast. In fact the opposite is true and most of these boats are some of the most coveted cruisers ever built.