Went through a few years ago.
Fees-bloody expensive cost around £150+ but good/great service along the way. This was (I believe) a 2-day pass from Inverness and out the other end past Neptunes Staircase.
Limited to (if I remember right) 5ish knots on the canal sections but unlimited through the lochs. And don't try and cheat because the lock keepers are in contact with each other and know the minimum time to go through each section.
The whole way takes a MINIMUM of two days. This is because of the lock time-waiting.
You also have to have 2 x long ropes for tying up as the surge from the gate openings do move you somewhat.
We didn't actually NEED them as we were fortunate in tying alongside someone's boat instead.
Also, from memory, slip launch sites were few and far between. Didn't bother as we were sea-to-sea.