As SC says, if it sounds good, then stay with it and crank it up
. At the end of the day, it's your total rig end to end that produces the amplification you want and all the bits need to work together to produce that.
But to answer the question for yourself, try MP1 > MosValve > cab on it's own and crank it up loud (MosValve vols should be at least 3/4 and adjust overall vol with MP1 output), this should sound really good with plenty of headroom (albeit with no FX) but should definitely not be thin and lifeless, you may need to tweak the patches (so maybe set up a new bank to play around, copy patch 1 (Marshall) to the new bank (e.g. to 113)) and tinker a bit. Then I'd add the Intellifex, as you are chaining through it you need to get the input and output gain right so overall volume shouldn't change and mix in some effects, then introduce MCII to taste.
Or just not worry about it and enjoy
though if MP1 sounds thin and lifeless without MCII, seems the patches could be better tweaked.