I spent a night many years ago (mid 1970's) inspecting the image of an f/15 Meade 4" refractor (very much like a Unitron) and an orange tube C5. I found at similar magnifications (about 100X) in each scope, set up side by side, the C5 always had a brighter image. I remember specifically studying M27 in each. The center of the field of view in the C5 was good with coma hampering the outer extremities of the field. I believe I was using Kellner oculars at that time. The limiting magnitude in the center was very close with mabye a nod to the C5. The flatness of field and contrast in the refractor was superb. Every star in the refractor out to the edge was excellent and pinpoint. I was impressed with each telescope at the time and I personally owned a 12.5" reflector with a 41/8" f/15 Jaegers piggybacked. The Meade had more contrast than my Jaegers which I attributed to much better baffling in the Meade.
Since that time, I have owned 2 C5's. The first was an orange tube. I bought it second hand and it was essentially in perfect condition. However, it had much field curvature and coma and I used several different oculars. Unfortunately, it was stolen from my house. Thinking hard, I decided to replace it. I bought a new black tube around 1985. Even though of that time period, it really turned out to be excellent and I still have it. I have compared it to a 5" Mak and it was too close to call.
So if you want the best star pinpoints, stick with the refractor. Again, at f/15 and at 4" diameter the color correction is going to be very good and nothing is going to beat it. If you want a little more aperture, a good C5 is hard to beat. Recent achromats of 100 to 120 mm diameter and f/6 to f/8 to me are disappointing with too much CA. I have now an 80mm Lunt ED and find it very good and a great compliment to my C14. Of course, an ED doublet in 100 to 120mm is great at f/6 and greater with a bit of field curvature at low power especially with my ancient eyes.
If I had a good 100mm ED doublet, I would probably want at least an 8" SCT to compete. But again these are different scopes for different purposes. Again, as noted elsewhere, it is great to have a smaller ED...80mm or so...for wide fields and excellent contrast and also a larger Mak, SCT or Reflector to go deep.
I guess I have gone far off topic!