Mak vs frac for planets...
The issue here is chromatic aberration at play. Looking at your signature, smiles233, you will not be gaining anything by getting a refractor that your Maks, or your 8SE for that matter, are not already providing you. If anything you will be introducing chromatic aberration unless you start looking at ED refractors to help control this, and this means much bigger $$$. An achromatic refractor will be a significant step backwards from your current scopes because of this aspect.
And on a Voyager 2 mount, a 4" refractor will begin to test your patience as it will start wobbling every time you touch it - a 4" refractor at high magnification on such a mount is not a great combination. While you have a 100mm Mak, its smaller, more compact size means less moment issues are at play compared to a long tube.
I certainly understand your frustration with poor seeing conditions. I have the same problem where I live. And like you I have a variety of telescopes. Larger apertures are more affected by poor seeing - something you may already be aware of (I am assuming because of your question). In all honesty, the only two things I can recommend to you:
1, Patience. I know it is not much, but there is nothing more you can do. A different scope won't help you.
2, Adapt your viewing. If seeing conditions are not much chop, then you need to adapt to the conditions. If you can't max out the magnification then your only option is to drop the magnification.
My preferred scope at home is a 9" Mak, and for many years before that it was a C8 (like your 8SE). And being plagued with poor seeing I have no choice but to adapt my planed session to suit the conditions. OK, I can't max out the magnification, then the only two options I have are either drop the magnification and work with that or pack up. I do have an ED80 refractor that I could use instead, and it is a nice scope, but I don't use it all that much. And if I had a smaller Mak or SCT I wouldn't use it any more than I do the refractor. And an ED80 still shows a small amount of chromatic aberration that my 9" Mak doesn't.
Most nights I pull out the Mak (or the C8), the most I can push it to is around 250X, and I am happy to work with that when it comes to the Moon and planets. If seeing doesn't allow for 100X I will normally do something else. The smaller scopes I have I use for other applications.
When it comes to the planets, aperture is the only route. You already have that with your 8SE. You already know the differences between your 8SE and your smaller Maks. A refractor is not going to help you if seeing is the problem.
What a shorter focal length refractor will do is provide you with a rich field scope if you look at an f/5 instrument. A 4" f/5 or 5" f/5 frac with a nice 2" 30mm eyepiece will provide you with a delightful situation that will very nicely compliment the high magnification beasties you already have. I LOVE my modest 4" f/5 achromat - a stonking good RFT I know its high magnification shortcomings, so I use it to its strengths I keep the magnification right down with this scope, and with an 80° 30mm eyepiece this little scope gives me a 5° true field of view - HUGE!!! It cost me little and it is a low magnification monster!
The sketch below is of the Eta Carina complex that I did with this modest 4" f/5 achro - a view none of my other scopes can provide!
Question, did you render the lunar formations entirely at the eyepiece?
Really you are able to draw DSOs like that at the eyepiece? Your are are quit capableble to render the limb like nobody
I have ever run across. Interesting thanks for sharing.