It is amazing what difference tube lenses make
Here are two pictures of same ant specimen (purchased online), first one is using Raynox DCR-150 as tube lens and second one is using a 70-300mm telephoto lens as tube lens. The Raynox is clearly out performing the telephoto lens.
Both were shot with the same PLAN 4x 0.1NA microscope objective and were set to about the same magnification. NO sharpening done in software, only cropping and contrast adjustment.
Not sure about color saturation difference because the Raynox is on a Canon 550D and the telephoto one is done with Nikon D5200, but as far as sharpness is concerned, Raynox is the winner.