Samsung Galaxy Ace - HID Bluetooth Keyboard Connection?
Bluetooth was enabled early on in Android (1.5 or 1.6 iirc) So any limitation in that regards is from your specific device and not the platform itself. 

I have successfully used HID bluetooth devices with: Samsung Galaxy Nexus, and HTC Evo 4g LTE, Toshiba Thrive, Acer Iconia A200. 

I was unaware that there were any devices that disallowed HID device connections actually.

In general though Nexus [anything] devices are the least limited devices on the market at any given time, so I'd say you can't go wrong with one of those.