I just bought two Vintage30 (110 euros each in Toulouse) to replace two original G12T-75 on my Marshall 1960A. I put up every two (on the advice of the seller) because they have an efficiency 3dB suprieur over G12T-75, the distribution is better and more homogne.
When I changed, what diffrence ... I still can not. I have a 100w head H & K Triamp, the sounds, they are clear, crunch or saturated, have all changed over high mdiums, DEFINITIONS better in the low (I September 1 strings, Septimus is a LA) and more than prsence. I play in a band and everyone felt the diffrence (I'm also quite agree with the opinion of the Previous HP). One hears much better, more distinctly. The bad is that his cot is very colorful but hey, with all the advantages that the HP amne ...
I await the arrival of two century vintage, to eliminate this hrsie what the G12T-75 ...