Accept bitcoin easily without strict terms of services? I'm interested in starting a gambling site, it has been difficult to find an easy way to handle user funds.

Solutions such as Bitpay or Coinbase disallow usage for gambling. 

BIP32 blockchain notifiers like Mycelium Gear appear to be vulnerable to spam attacks and difficult to scale.

I've looked into interacting with a full node but things seem to get complicated very quickly at scale.
I wrote a webshop app using armory daemon. It can generate bitcoin addresses on the fly and not put any funds at risk since it's using a watch-only wallet:

https://github.com/goatpig/BitcoinArmory/tree/master/webshop

If you're not afraid of a little code, this should work without having any dependency on external services.