This reminds me of one of my oldest topics years ago before I realized he was untouchable Bastion Rework
I feel like heroes should be “experts” at their unique trait. For Bastion, that feels like transformation to me. Like Yagorath, I want to see him go tank mode mid battle to quickly reposition and then go Sentry to fire down a lane. (Tank mode shouldn’t just be like how it is in ult, though)
Transforming should feel like a much more fluid process – they actually buffed him that way years ago and it felt nice jumping and transforming in one smooth motion.
This speed buff idea sounds interesting but it also sounds like it just helps him retreat a bit better. Kind of makes Bastion sound like Chunky: 76 with a conditional sprint 
I’d rather he get changes that allows him to engage better without becoming Optimusprime: 76