IMO, 20w50 is hard to beat for all-around use in an air-cooled MC engine of any design. I have never followed where the concept becomes reality that 20w50 would be too thick in spring or fall, and looks like Yamaha is beginning to agree by retroactively making a specification alteration. But I wouldn’t think twice about continuing with 20w40 either as you’ve probably been using that for a while with no issues and you shouldn’t have any issues with it.
My local Walmart here still has all flavors of ST motorcycle/ATV oil for $4.98 a quart, checked again this morning. I have picked up enough 20w/50 to cover me for an oil change down the road on top of the other different oils I collect to use in my motorcycle. Reality is I am an oil collector.
I admit, I have 8 qts of Red Line 20w50 MC, 6 qts Castrol Syn 20w50 MC, 4 qts Valvoline 20w50 conventional MC, 4 qts SuperTech 20w50 MC, 4 qts M1 10w40 4T, a gallon of Delo 400 LE 15w40, a gallon of T5 15w40 and a 5 qt jug of M1 15w50. Always buying the stuff on sale, even the Redline off eBay. $4-$6 a quart isn’t gonna lose me any argument about overpriced motorcycle oil. That’ll cover me for 10+ riding seasons at 5,000 miles a year. Only oils of those listed that I have not run yet are the Redline 20w50 and the Super Tech 20w50. All the others have seen at least one OCI in the ZRX over the years, in addition to M1 20W50 V -Twin and a few others I don’t have on hand.
Carry on.