The Bristol 40 is a derivative of the "Finistere" a S&S / Hoyt design that dominated long distance racing during 60s. Other derivatives / similar boats (hulls) are the Block Island 40 and Bermuda 40.
Yes, they are initially tender, need to have FLAT draft forward sails but typically are stable well through the upper 30kts of wind; need taught forestay and well balanced helm (via well 'shaped' sails) or they can easily 'skid off to leeward'. A precise helmsman, quality flat luff entry sails, a good slick bottom and all of these boats 'fly'. You want to keep the ends 'light' in these boats or they tend to 'hobby horse' in a seaway. Heeling is not a big deal, you just reef earlier, and get used to it. If you plan long distance sailing, you dont usually plan to BEAT to windward for days on end, you wait for the correct wind window and reach/run there.
The propensity to heel was not an afterthought, it was purposely designed that way as a 'racing rule beater' so that when heeled, the large overhangs added to the waterline length; hence, the boat is faster when heeled.
Finistere was a *race* boat, and the derivatives / same hull hull design are not optimized as dockside garages due to the narrow beam (as re-defined by todays standards). These boats area bit more than 'raise the sails and go' ... youll have to learn sail shaping and helm balance on-the-fly; and, you will learn to reef (properly).
There still are a lot of well maintained Finistere derivatives found in 'the islands' and in Maine .... most are still 'head turners' - graceful shear and with large overhangs. If set up well, and skippered well ... are a pleasure to sail. All these boats are B-e-a-u-t-i-f-u-l and take a lot of maintenance to keep them that way.