the cost of the private VIP guide service is $125/hour with a 5 hour minimum.
You do NOT get front of the line, but the guide will run around and get fastpasses using your tickets (in other words, the guide becomes your fastpass commando), but the FP works just like for 'regular' guests. No special FP advantages.
The only preferential treatment is reserved seating at some shows.
However, considering the minimum you have to pay is $625, that's a bit steep just to get preferred seating at a few shows.
I considered the service (and spoke with them a few times) but since it didn't include front of the line, it wasn't worth it to me to pay someone to be my commando (and then sort of be an 'odd man out' to our family unit). What we most enjoy about the parks is the 4 of us, just hanging out together, regardless of what it is we are doing.