You can just loosen the coolant temp sensor to let the air out of the head, but the hole in the stat is nice if you suddenly suck air and don't realize it.
A lot of times you can get away without the hole if the stat doesn't sit tightly in the housing- it might leak a bit.
The BMW I used to have had a bleed screw on the thermostat housing that worked nice.
The 261 doesn't need a hole in the thermostat if it has a bypass thermostat, the bypass takes care of the air burp.
The only thermostat I've ever seen that had a factory burp hole was a Robertshaw thermostat, and I haven't seen a new one anywhere, the only ones I can ever find are Stant.
