Oliver
To go back to your original question "what the differences between a Series 3 Roadster and a Trad +8" , I think you can sum them up in a few words , exhaust note and low down torque.
The exhaust note of the full V8 is melodious and addictive, especially with a Librands (or similar) exhaust system. You will really enjoy driving through tunnels and changing gears "just for the hell of it" . I like the Roadster very much , but another Morgan enthusiast summed the experience up pretty well . "The Roadster sounds like chamber music, the +8 is the full orchestra."
The low down torque is what makes the +8 so relaxing to drive, you can boot it up through the gears if you want to listen to the engine note , or you can leave it in 5th and just surf the torque wave. I guarantee this is the most important difference you will notice while driving.
You will miss the 6 speed gearbox , but really 5 is enough. You may miss the higher revving nature of the V6 as the V8 rarely needs to go above 5,000 rpm. Most other things will be remarkably similar.
The sump is much higher on the +8 , so although you still need to treat speed bumps with respect, they are not quite the heart-in-mouth experience that they are in a Roadster.
You would be going from a newer car to an older one , so make sure that you buy one that has been well cared for and not been hibernating for long periods. As the trad +8 became extinct in 2003/4 most of them should have at least 30k miles, and preferably more.
Other than that it will be a very subjective decision based on personal choice and preferences.
Good luck
