Diameter of Primary Mirror: 127mm
Telescope Focal Length: 1500mm (f/11.8)
Your telescope, at f/11.8 would be considered a slow scope. A telescope with the same aperture (127mm) but a shorter focal length - say 600mm - would be an f/4.7. That would be a "fast" scope.
In this example, where the only change is the focal length of the scope, using the same eyepiece, the faster scope will provide a much wider field of view and a much smaller exit pupil. The magnification of the image will also be greater in the faster scope. So what's the advantage of your slower scope? It is much more tolerant of eyepiece construction. You can use eyepieces that cost significantly less than the premium "green letter" EP's. A slower doublet does not show color aberration as readily as a faster doublet and costs much less to build than a similar size triplet.
Your narrow field scope is well suited for planetary work.