Seriously, what retarded riders are you hearing this from?
I rode for a year on a Kawisaki Vulcan 500 and on the 400 series highways in my second year of riding. It's not what you ride, but how you ride it and your ability to control yourself and the bike.
Can your vehicle do a 100km for an hour or more? Because the last time I checked that's the speed limit on the 400 series highways. And since the only lanes that have a blocking position are the right and left, You should be fine. The right lane rarely exceeds a 100 so the need for extreme accelaration for passing is also rare. Stay out of other drivers blind spots. With regards to truck, stay in his mirrors or be in front of the truck so that you can see the truck in your rearview mirrors.
Try to practice out on Sunday mornings when traffic is a little lighter. Good luck and safe riding. God Speed.
Pretty sure any advice given to him so far from his friends outside of this forum, was maybe taking into account the 401 especially, and its infamous/dangerous disappearing right lanes. I have often run the 401 when even the slowest right lane was doing 120/130, and if you have just merged on...let's say 401 WB at Weston, where lanes are short and uphill, and if you have to get across 6+ lanes to exit off to the left just half a km up, then those really are times you wish you had a lot more grunt. Factor in headwinds etc and issues become compounded.
As has been mentioned, it is ridiculous to compare small bike capabilities going by only displacement. While I agree that the 535 has enough to do this task, in some spots on the 401, I'd feel a lot more confident doing it on a 500R. The 535 is no slouch, but it is also no ball of fire as 535cc's might suggest. And it was never designed to be. It was designed to be a relaxed ride cruiser for those short in the inseam and who simply prefer a cruiser over other styles. Even the Vulcan (which has the Ninja 500 motor, but tuned for torque at much lower revs at the cost of hp on the upper limits, compared to the Ninja) pulls harder than the 535 once out on the highway.
So that my comments can be interpretted the best, I am one of the ones who will not defend a CBR125 on the 401. Perhaps at 4 am in the morning it is safe enough, but that little bike is out of its element in many areas/certains times of the 401 and anyone who has a 125 and feels they are going to change my mind, I can assure you, there have been times you were in
in the way (even if at a legal speed) and a sitting duck.
As for the OP, I applaud getting other opinions on an open forum. Given his experience, defensive driving practices, I'd say he should be fine for all but the worst case scenarios he might encounter on the 401, and in those circumstances, there are always other options/exits that, while they might be out of your way a little, can still get you where you want to go using another merge lane elsewhere with a bit more room for more relaxed accelerating.