For the 208 Adventure that you're looking at/referring to, the hull switched over to a SeaV2 supposedly in 1993, or at least per the below linked thread on this website, and the 228 Seafarer switched over in 1992. I think what the guy might be referring to is a couple different things, but most likely the main one would be the transom. I believe it was 1997/1998 when they switched from standard marine grade plywood to a product called Greenwood XL. The latter product, Greenwood XL, supposedly is much better at resisting moisture and is supposed to be a superior product. There are several guys on here though that have had hulls from 2004 and newer that have also had to replace, or partially replace, their transoms though. So, it's not really a get out of jail free card or anything, and if the water intrusion is substantial, you can/will still have issues. I think that the bigger issue here would be the bang cap/plate, which is found on a 208 Adventure as well as several other Grady White models. The bang cap/plate can become damaged, warped, sometimes even missing entirely, etc... to where you can get water coming in from that spot into the transom.
I've got a 228 Seafarer, it's a 2004 model, of which they have a fully enclosed transom as well as transom bracket on the boat. Which is quite nice in that you don't have to worry about that bang cap/plate, and the chances of having water intrusion are considerably less, unless you've got some structural damage or something else. I know that Grady White also made some differences to the hulls/transoms of some of their boat models in the early 2000's to "beef them up" a bit in order to allow for the added weight of 4 stroke motors, which came out in I believe 2002/2003. On top of that, the 208 Adventure/228 Seafarer, as well as I'm guessing a few other models as well, both had a different design for the models come out in the 1998 model. The 1997 and previous models are the older looking ones that have different trim around the windows and windshields as well as oftentimes have woodgrain inserts in the doors, etc. 1998 and newer models pretty much use only starboard and have a different style of window trim as well as just look different overall. I wouldn't necessarily say that the dude is "wrong", as when I was looking to buy my boat, I was only looking at 1998 and newer models, though obviously I was looking for the newest that I could afford, and am glad the 2004 that I bought came up and that I bought it.
1. What year did Grady White start building the SV2 Hull?
The SeaV2 hull design was implemented on Grady-White boats in the following sizes and years:
28 ft............1989
26 ft............1991
22-25 ft.......1992
208-209......1993
192.............1994
180.............1998
2. What is the Sea V2 hull?
A Continuously Variable Vee Means Soft and Stable
A SeaV2 hull design has no two places on the keel where the deadrise is the same. The vee continuously sharpens from the transom to the bow stem. A SeaV2 hull design with 20 degrees of deadrise at the transom will...