Boss VF-1 Effect Processor

Hi!
I am new to the list, this is Hector from Barcelona, Spain.
I just got a VF1 and bought a midi single pedal to increase patches. 

I found something quite annoying: in certain patches, in the 
beginning the sound is lower than usual (few seconds), so it makes a 
bit weird to use different programs in one song. But, as I said, I 
am new to this unit, so maybe there's something I'm not doing well.

Another question: I find it difficult to get a good distorted guitar 
sound. I finally gave up going directly into the mixer (a bit 
frustrating: I got better sounds with my tiny PX1 Pandora!) and I am 
trying it into a good valve amp now. In general, do you think this 
is a good guitar-oriented unit? I like the clean sounds and the fact 
that is perfectly transparent when bypassed, but.. well, any 
recommendations with the distortions?

Héctor