Straffo, it was pretty bad. One pilot account says that a flight of new typhoons dove in on some enemies, and 3 of them lost their tails and died. 3 in one attack. That's pretty damn bad.
There was another acount where a pilot was learning to fly the Typhoon, made too fast a dive, and literally ripped off something underneath the airframe... Couldn't slow down below 200. Made for a hairy (AND scary) series of landing attempts. Ripped off a plate of skin underneath the belly or some such thing.
The plane was a widowmaker, through and through.
EDIT: Re: 202/205 12.7mm they are about the same as 50cal, yes. 12.7mm is roughly half an inch (the 13mm the Germans had is closer, though)
EDIT2: Think about it, 1 inch is 2.6cm (26mm)