Hi S'
I had exactly that question last year and after trial and possibly error too! I went with the plus 4 with the Duratec engine and fird MT-75 gearbox.
Here's why!
Roadster is a great car but for me on the mainly B roads I drive in North Wales, much like yours I think, I found it too powerful driving the constant tight bends. its an engine that needs revving high and I just couldn't balance my driving and found it tiring.
4-4 is a light and smaller feeling car and loves to be thrown around and is very forgiving but would need muchos extra spent to give it the power to weight ratio that I wanted but was tempting as the cost is considerably lower than the other 2.
Plus 4 For me it was like the three bears story, I just felt right in it and knew that I'd found the right bowl of porridge! I then researched the options and quickly settled on the original Duratec engined cars up until 2011. I tried the later options but knew I wouldn't be buying the GDi version. Plenty of info here as to why that is the case! The Mazda gearbox does feel nicer though although In the end I went with the MT-75 ford box, yes the change isn't as slick but the Mazda box has two problems for me: 1 mated with a Duratec variant engine the bell housing sticks below the engine and is venerable to being hit and damaged (badly). Its even lower than the chassis protection bar on the chassis and is in fact the lowest part of the car!
2: The gear change linkjage when fitted to the Morgan is fragile and its not will it fail but when...... try and get a replacement!
The Ford MT-75 was the gearbox fitted to the Sierra saphire cosworth and you don't hear those owners complaining about it!
Between 2011 to 2012 ish the original Duratec 2.0lt was fitted to the mazda gearbox and if you feel you need that box and a plus 4 this might be the way for you to go!
