Sorry for late response. The effect really is minimal. However, there is some. I'd prefer to have my miner with mini heatsinks rather than without. But that's just me. 
Anyway, I'm going to sell both of my miners now. Including the 3D printed mods.
I've also managed to make them work very quiet while still being quite cool. The recipe is: 2 Corsair SP120L (not without L) fans, exhaust side fan duct and top & bottom enclosure of miner's heatsing. The front fan is screwed directly onto the miner while the pull fan pulls the air through the fan duct. The pull fan does all the cooling (it can work without) and the push fan gets some heat off the external heatsinks. With stock frequency I can have both fans working at 70%, which is very quiet, and miners would have HW errors as low as what they usually get with stock fan and stock frequency. With fans at 100% I can overclock the miners up to 393.75MHz for a stable 24/7 run. I'll post some photos of that setup/build soon.
Anyway, I'm going to sell both of my miners now. Including the 3D printed mods.
I've also managed to make them work very quiet while still being quite cool. The recipe is: 2 Corsair SP120L (not without L) fans, exhaust side fan duct and top & bottom enclosure of miner's heatsing. The front fan is screwed directly onto the miner while the pull fan pulls the air through the fan duct. The pull fan does all the cooling (it can work without) and the push fan gets some heat off the external heatsinks. With stock frequency I can have both fans working at 70%, which is very quiet, and miners would have HW errors as low as what they usually get with stock fan and stock frequency. With fans at 100% I can overclock the miners up to 393.75MHz for a stable 24/7 run. I'll post some photos of that setup/build soon.
Ah, thank you for letting me know, even though late. I have a small pack of 100 mini heatsink, but i did not place them on the S5 since the chip's top are on the other side of the board. Do you put the heatsink on the copper plates?
Also i'm guessing you will have no problem selling the S5 at crazy price right now, but if you end up being interested in shipping to Canada, drop me a quote for one/both.
