I have some thoughts for you about your quetions regarding your rear suspension.
1) the markings L146 and L250 do not indicate the spring rate.
2) Moving the locator rings for the remote spring preload adjuster, or changing the spring requires a SPRING COMPRESSOR.
3) your comment; "yep almost no free sag 25mm rider" doesn't give me enough ACCURATE information to assess your spring needs.
But, I will say that the spring may be too soft for you.
It will be necessary to do a proper sag measurement using the method we use for us to help you. I can share with you that method if you like.
It is absolutely necessary to know exact to the millimeter the rider sag, plus the free sag, to determine proper spring needs. We have a procedure.
4) unless you have, or know someone with a shock spring compressor, you will need to send it out. It is the only safe way to handle changing a spring or moving the preload collars.
We can help you with all this; both selection and fitment.
I will tell you this; It is much better to be able to touch the bike in this process, to check spring choices and preload range of adjustment. That is why Tracey asked if it was possible to get your bike to VIR while I was there. We meet many customers there to put hands on.
I go to VIR about once or twice a month to races and trackdays.
You can call me at 404 297 8464
GMD Computrack Atlanta