Thanks for everyone's input. I have decided to get both V-cap and Bybee upgrades.
Talked to Simon, of Spectron, yesterday. Counter to what I was thinking he felt that if he had to choose between the two upgrades the Bybee does the most in enhancing amp performance. He stated that the V-cap gives you more of what, he feels, that the Spectron already offers, warmth and liquidity. He went on to say that the Bybee gives the Spectron another dimension that it currently does not really have, palpability. He used this word more than once so I looked it up just to make sure I really understood what he was saying.
Palpable: that can be touched, felt, or handled; tangible.
I have my own interpretation as to what he was tring to say and I'll leave you to your own interpretations. In any case I went with both upgrades. Thanks again.