Those TB6600s are nice and cheap for any number of tinkering type projects, but in my testing, they aren't fast - and performance varies depending on the motor. You might want a cooling fan on them if you are going over 2A. The Acorn etc will have way more 'pedal' in terms of pulse stream output than the drives are capable of going AND those drives also are a bit noisy on the top end of the RPM range, so plan on the motor locking up/puking sooner than later. But...if you're just tinkering and doing low speeds stuff, they're hard to beat. Besides, the voltage cap on the drive really limits high RPM/top end speed anyway.

No doubt you've probably heard of them already, but Trinamic makes some pretty cool stuff worth a look...