This seems to be more of an imaging question. I have no idea about the imaging aspects.
With regard to visual, I have the ES 127 Mak (f/15) which is the ES clone of the same OTA, but with a better back plate arrangement than on most of the Meades--allows access to the collimation screws. For my sample and my eye, I have found that in very good seeing that a 9mm eyepiece for ~211x is about the limit for maximum planetary detail. Most of the time seeing limits me to a 13 or 11 for 146x or 173x.
When it comes to theoretical limits used in specs, they are generally provided using a 50x/inch rule of thumb. This is typically about right for me with a well corrected ED/apo refractor on planets, but obstructed scopes like cats and newts are a bit different. The combination of mirrors and sometimes large central obstruction (e.g. ~40% in 127mm Maks) reduce the contrast. The result is that I find the optimal detail is somewhat lower/discounted with large obstructions. With my SCT and Mak the result is an optimum magnification for planets in stable seeing that is about 40x/inch, give-or-take a little.
Different folks have different eyes and preferences, but much of this comes down to what level of magnification begins to reveal the diffraction effects. On a suitably bright star I can begin to see the first diffraction ring by about 1.5mm exit pupil (~17x/inch.) Some with sharp eyes might be able to see it at 2mm exit pupil (~12.5x/inch). Most will be able to detect it by 1mm (25x/inch). The 0.5mm exit pupil (50x/inch) is at about the point that diffraction effects begin to noticeably blur extended objects. One can continue to increase magnification but it is unlikely to reveal anything more, and it might even make it harder to discern detail as the image becomes dimmer. [Note, this resolution loss is somewhat different than the contrast loss from reduced transmission and from the obstruction of reflectors and catadioptrics which result in some additional discounting as described earlier.] Exit pupils somewhere below 1mm tend to show more of the structure in the eye as well (floaters, some texture, etc.)
My advice with respect to finding optimal planetary magnification for a scope is to approach it incrementally, beginning with a magnification that should be useful on most decent nights. ~150x is useful even on mediocre nights when stability is not good. ~175x or so is usually there on decent nights with the 127 Mak. ~200x is for the better nights. If a person starts with an eyepiece that is nearly always useful for planetary, then adding the next increment will likely reveal more on some/many nights. If that one still seems to have some room left, then add the next increment. Eventually one will find that the final eyepiece never seems to be providing more detail, even on the best nights.
Starting at 50x/inch is unlikely to prove useful in that regard even with perfect optics and perfect collimation. It will almost certainly overshoot for planets. At 50x/inch one is not accounting for obstruction effects, or more importantly seeing and thermal effects. Most of the time seeing will be limiting.
So where will 50x/inch or even higher prove handy? Very close double stars. With tight double stars one wants to see and inspect the diffraction patterns associated with the spurious disk and first diffraction ring. This is a range that eyepiece and Barlow combinations cover well.
