for other algos then all scales pretty the same so you can chose if you want density for a premium or if you want lot of rig to administer and pay a lil less
If you have more rigs, that means you're paying for more motherboards, CPUs, RAMs, racks and power supplies.
It might be more cost-effective to get more expensive cards.
the price for cpu ram and motherboard and rack is very minimal. and with lesser cards you will save a lot on psu.... doesnt matter what careds you buy up to the 1070 the price of the system (including risers psu and rack) will be roughly 25 - 33 % the cost of the cards :
eg
cpu ram mobo risers for 1060 to 1050ti will be roughly 115 EUR for a 5 gpu system
psu 89 eur (750w 80+ gold)
for 1070 you will need much more juice so psu alone will cost roughly the double if not triple.