There is no real resolution to the transom issue, it comes down to previous owner's care and use. there was 0 problem with older Grady transom design, anyone who says there was is 100% wrong. The issue lied with installer's as well as owner's not knowing how to properly install transducers and take care of thru hulls. Part of the problem on earlier Grady's was the use of plastic nylon thru hulls that over the years cracked and allowed water to seep into the transom, but the transom design was not the flaw, the thru hulls were, and owner's not knowing when the thru hulls required replacement, or not wanting to spend the money were the biggest issue, some just did not know. Moat boaters out there have no clue how to maintain half of the stuff on their boat. I've seen many "professional" electronics installers improperly install components into transoms, transducers and trim tabs were the worst. Any drilled holes need to be sealed well with 5200 since your below the waterline, chaulk and other products do not do the job, over time they break down and allow voids where water got in. Newer models have less issued due to newer thru hull usage that do not break down, but I've seen new Grady's as well as other boats with transom rot due to improper care, and I've seen older Grady's with no issues what so ever. Only way to know is a survey.
Scout uses core in their transom's, you'd think they would not have problems....well for a while they did, space between the fiberglass and core existed and the void allowed the glass to slap the core and actuall broke it into a powder, now you have a sandwich with no strength in the middle. I've seen core get wet and soggy too from improper adding of accessories. Solid glass can have issues too if air bubbles or voids exist. There is not 100% fool proof method or fix although some are better then others. Only good workmanship can do things right and prevent issues, and every builder has their own ways. Wood is still used by many and from builders and designers perspective and a design stand point is still one of the best materials today and is still used in boats big and small. Some brands are getting away from it, but not for longevity issues or strength, but to cut weight or to use no wood as a marketing gimmic...which it is, just that and nothing else.