I will dive into that. I'm using smaller transformers so I don't have to make the compromises Fender and Marshall made. Although they made great amps, it doesn't mean they're perfect. Leo often cut costs, where he could, and Marshall also did some weird stuff.
When you watch amp-tech's and builders on youtube, you learn that the existing designs can be improved. But if you improve them too much, you'll lose the original quirks that makes the tone.
Yes...all of this is true. I also enjoy taking these old circuits and throwing in some modern twist to come up with something unique. It's important to remember though that the original designers often went through multiple prototypes until they came up with a proven layout that was quiet and dependable in every chassis that they wired. It's perfectly acceptable to throw in some modern changes but just try to stick with some of the tried and true rules of lead dress and you will end up with a great finished product.