I've been running the ATE type for a couple of years now. Its DOT4 and I have not had any issues.
Some of the fluids do readily absorb more moisture from the air which can lead to corrosion. A lot of the high performance and high temp fluids do this but they are also supposed to be changed out at least once a year.
Mine gets flushed at least once a year. A lot of the guys running the MotulRBF and similar fluids should be changing theirs more often but probably aren't. Honda most likely puts that note in the manual about the Dot4 to cover themselves from people swapping to "track day fluid bro!!!
If the bike used a Watt gear power then we would have a controller available for it with more. I ran a gear ratio calculation with the MOTG nickname and assuming that the bike has 26" wheels the axle sprocket needs to have 25 teeth for a 15 MPH top mounted. Here is an screenshot of the gear ratio calculation. MOTG has a 10 blue sprocket which can be used with 41 or chain so a 41 or moving would be needed for the axle.
Then they try and get their brake system warrantied. Tons of people run their OEM fluid for way too long anyways.
That stuff does absorb moisture and gives that spongy pedal feel. Most people don't know the difference and assume that brakes are supposed to feel like that.
If you want to run Dot4, go for it. Just understand what you are getting and what the new maintenance requirements will be.
Also flush your system well and be sure to get all the old fluid out.
I just read on a FB group that I belong to that you cannot use DOT 4 brake fluid on our cars. I've never heard this before so I'm wondering if.