The short answer: If you are unsure about this, take 4 wheels.
The only reason why anybody would use only 2 wheels, is to make grinding easier.
When you grind in between the 2nd and 3rd wheel, these 2 middle wheels are actually super in the way. Because wheels are grippy, if one of the wheels sticks on the obstacle you are grinding on, you might fall.
The sad thing is that when you are not grinding, then you want those extra wheels to have a smooth ride with. 4 wheels will give you better feeling with the road. The more points of contact you have the better the ride is when the road is kind of bumpy. Your manoeuvrability and speed are also allot better on 4 wheels. In short, 4 wheels make everything better, except grinding.
The dream is to have a skate with 4 wheels and also a big grind block. The USD Aeon solved this by having a one piece boot so that there would be no constraints in the wheel placement because of the position of the frame mounting.
A way to get the best of both worlds for all other aggressive skates with a removable frame in the UFS mounting system, is to get the Oysi frame. The Oysi frame has a big grindblock and still has 4 nice wheels.