Stu, as a basis for comparison with other (bigger) scopes, a small apochromat will not work. The reason has to do with the wave nature of light (i.e., diffraction) and the resulting limitations on the resolving power of a scope.
It is easy to see stars as beautifully concentric and very well defined Airy disks on a small aperture scope, because the diameter of the Airy disk will be large (inversely proportional to the aperture of the scope). The smaller the scope the larger the diffraction rings, and hence easier to see, and the less affected by an unsteady atmosphere. You will see textbook perfect Airy disks at relatively low magnifications in a half decent 70mm scope. You will rarely see them in a 300mm, because seeing almost never permits a steady image at the high magnifications required to actually see the diffraction rings.
But these perfect diffraction rings are precisely why you cannot resolve fine details in a small scope. Every point on the true image is replaced by an Airy disk in the image you see through the scope, effectively blurring the image.
Chromatic aberration on my ED80 is non-existent as far as my untrained eyes can tell. I certainly wouldn't want to go smaller in aperture. The tube of the ED80 is oversized (100mm) which might put you off if you want a really compact scope.
You're most welcome to check out my ED80 at Star Camp.
