That's a really nice kit. You're going to notice a big improvement from a mini-cig. Dual coils may or may not be better than single coils. It's really kind of subjective. Personally, I'm not a big fan, but they're o.k. IMO, they really don't hit their stride until about 4 volts or so. With a lower voltage PV like a Riva, I'd recommend a 1.5 to 2.5ohm single coil cartomizer.
With a Dual coil, what you really have is two coils that run twice as cool as the same coil in a single coil carto of the same resistance. IOW, a 1.5ohm dual coil is really two 3ohm coils. Each of those 3ohm coils gives 1/2 the power and runs half as hot, as a single 1.5ohm coil. So, to get the same power, you'd need 2X the voltage, and you can't do that on a Riva or other single voltage PV. It's like taking two Rivas, taping them together, sticking a 3ohm carto on each one, and vaping them at the same time.
OTOH, if that dual coil carto is a 1.25ohm, it might be pretty good. It would be like vaping with two 2.5ohm cartos. You'll probably find the ideal resistance for a single coil carto or atty is 2 or 2.5ohms.