1. The official Makita blades are 165mm diameter, BUT the Festol TS55 blades are only 160mm. Thus there are more third-party alternatives available at 160mm than 165. I use both sizes in my SP6000k, but they have, so far, all been Makita ones (yes, Makita make the smaller size too, so be careful when purchasing - I wasn't!).
2. Thin kerf blades may not work well. They reduce the power needed for battery saws but in every other respect are a bad idea (more flexible saw plate == not-so-clean finish, increased risk of kickback, etc.). They will also, probably, muck up your zero-clearance splinter strip (discussed elsewhere - You'll see why if you draw yourself some diagrams).
There is a good reason for plunge saws having a much thicker saw plate than is common otherwise: it's to get a good finish. It makes the blade more rigid, and remember that the plunge saw blade cuts at both the front and back of its rotation (few people know this, I suspect). Correctly set up, the saw has a tiny amount of toe-in at the front, meaning the back of the blade DOES contact the work and cut into it.
3. These saw systems are intended to do a few things well only, and they are not general-purpose handheld circular saws (no matter what the adverts say). They are for cross-cutting wood fibres, glues, and man-made materials, in unstressed, dimensionally-stable stuff. THEY RIP CUT BADLY and, in the Makita case, not very safely (it has no riving knife, but the Festool does). Putting a blade on with a low tooth count, IMHO is a bad idea and won't give a good finish, no matter what you try to improve matters.
I have caused kickback on a few occasions with mine, by being stupid. I have a 1/2"deep, 3/8" wide gouge in my workbench that proves three things: 1. kickback can easily cause the saw to leave the rail, 2. the plunge system is no substitute for a proper blade guard, 3. I can behave like a total ***** on occasions, usually when I am in a hurry (which is potentially career-limiting).
You could use Festool blades in the Makita - IIRC they have the same kerf and plate widths.
Personally I have had excellent results from sharp Makita blades intended for the saw. The blades are not intended to be disposable: depending on wear and damage they can be resharpened several times, which cuts down the cost of ownership quite a bit, and makes much more sense.
The OP doesn't say much about intended use, nor why he dislikes Makita blades. Are they simply blunted now? Is there a saw doctor they could be sent to? In my experience, having a blade done professionally is transformational. I use Leitz tooling by choice (they have branches across the country), and I've had stuff come back sharper than when it was new.
So, a few disorganised thoughts above, but in my limited experience, the Makita blades are good, and there are many reasons for staying away from cheaper substitutes in this context, even Freud ones (usually brilliant, in my experience).
E.