I'm also thinking of adding some additional English estate pipes--presently, all my older pipes are GBDs from the 1970s or before. Presently, I'm looking at a Barling Fossil from the 1950s. Hacker's Rare Smoke speaks well of them. Experiences?
With 1950s Barling Fossils, no. With pre-Cadogan era English pipes, yes. Good ones are very good indeed, but expect considerable variation in smoking quality and taste from one example to another, even in the same company's products from around the same time. This will not necessarily correlate with high-end/mid-range/budget seconds designations, or with the status the company's products enjoy today.
Also consider it possible that you may, at some point down the road, decide to have some of their airways competently opened. The improvement that results can be noteworthy.