Difference between using couches and bannetons for proofing

Just a quick question. Does it make much difference to oven spring if you use couches instead of bannetons for proofing 73 - 75% hydration sourdoughs?

I cant afford a load of bannetons so have been using couches to proof my sourdoughs which are approximately 50% wholegrain/50% bread flour. They tend to spread a bit  - which is normal, the spring isnt as pronounced in the oven and the crumb isnt as open as a result. They still taste delicious and i dont expect a huge spring from a 50% whiolegram bread however Im just wondering about the role of the couche in all of this...any thoughts? Im currently baking 25 breads at one go so the price difference between 25 bannetons and 3 couches is alot...

thanks