I haven't driven the roadster with any of the rear suspension variants but i have a plus 4 with supersport engine, 2.0 litre Mazda MZR engine by Omex giving around 200hp and it makes a very lively chuckable Morgan. Matched to Mazda 5 speed box, the box of choice for Morgan , Caterham etc, its a lovely motorway cruiser easily returning low to mid 30s to the gallon. I would have thought handling the roadster with that big lump up front would be an "all hands to the pumps" experience. With the suplex front suspension set up front, Bilsteins all round and a Panard rod at the back my plus 4 handles about as good as it gets with a 1930s set up.
A lotus it ain't! I run an S2 Exige S with the Komotec engine upgrade, an S1 Elise sport 160 and an old Caterham crossflow. Driving the Lotus is consistantly exhilarating experience where the cars needs the lightest of input to get the response you want regardless of the rate you're travelling at as you'll know. The Morgan experience at speed (in Morgan terms not Lotus terms) you're hanging on to the wheel for support as the seats don't afford much in that depertment the car usually lands where you are hoping it will.
Brakes, i didnt rate those Indian things they are using but could not run to the AP Racing kit so i went for the Hi Spec Big brake kit from Peter Mulberry and have been well pleased with the upgrade, a great improvement and almost approaching the AP set up on the Exige and its on Pagid RS 42 pads.
See the Morgan in action on u tube Omex Morgan Plus 4 at Llandow. The omex engine is perfect for the Morgan and readily upgradable to get a few more BHP from without major internal work.