So far, i am on 200Mbps and have no problem since i upgrade exactly 1 year ago.
I had only 1 problem, due to fibre cable not working. SH technician replace & test speed is 200Mbps.
As i had no problem, last week upgrade to 500Mbps, without change of devices.
Problem could be due to the wireless router. I replaced mine recently.. Still having problem with 5GHz wireless signal for surfing when "out of sight" of router. Gave up and disabled it...