Brittney spaniels are wonderful smaller dogs with big dog personalities. If grandpa doesn't have running shoes and wants to walk up on the bird I think he needs to rethink his dog choice. Sounds like he is use to hunting flushing dogs that need to be in range to the hunter as they work. A pointer can work much more ground and hold the birds till you arrive. Release site birds are no change for Britney spaniels. I use to have Brittney's and changed to GSP's. Both are good dogs but notice some differences between them and had to hunt them differently to get there maximum potential out of them. The Brittney's are smaller and tougher then the GSP's. If there is a sent trail going into the thickest nastiest sticker patch the Brittney's jumped in head first and never looked back. The GSP looks at the patch and may run the perimeter to see if the bird exited it then goes looking for an easier bird. They tend to like the big open open country verses the thick and nasty. The short version is they tend to out run the Brittney's. Brittney's are great family dogs and are very loyal. I do agree with JO and Tbone partially. If Grandpa wants to hunt a pointer like a flusher he won't be happy. It sounds like he wants a change and has to be willing to change as well to hunt to what ever dog he chooses strengths. My Brittney's tended to naturally range closer than my GSP's. But then again I tended to hunt the thicker cover that other dogs don't hunt as effectively with my Brittney's vs the wide open cover I tend to hunt my GSP's in. Brittney's are ideal for west side release sites but are very smart and tenacious to take on east side wild birds. In fact, Pheasants are not much challenge for either breed I find. Pheasants are stinky birds that are easy for dogs to follow. I personally enjoy watching my dogs hunt a broken covey of quail the best. Grandpa needed worry if he hasn't ever trained a pointer the pointing is natural instinct. You don't train them to do it you only reinforce that behavior with practice.
Good luck and have fun with whatever Grandpa chooses.