I couldn't help myself. I have a 300H and 1x15 V-Type combo also. I have played the 300h since 1998 when I got it new. I have played through a number of other heads, but this is it for me. I fell head over heels in love with the tone immediately.
So now a new old stock 600H. I can't wait as I don't have it in my possession yet. But I have a feeling this will be getting a crap ton of use..