Also just a thought, but if limiting the hashrate spreads among new coins, a captcha should be required to create a mining account on the hashrate-limiting pools, otherwise large farms will just automatize the creations of lots of accounts xD
This is an absolute must otherwise it'll be bot city.
Does hash limiting also rule out the use of rentable hashing power as it will all come from the same IP?
No, you can still rent but if the limit is 50MHs, then you will have to rent a rig smaller than that, max 43 MHs because sometimes the rig goes higher and if it trips the limit the worker is briefly temp banned.