When I started catering BBQ I went into the local market with the idea of introducing the on-site "competition" sampler sort of meal. The market and economy locally isn't in the right place, but there is a demand for pig roasts.
In 1 hour in any direction I only have 2 commercial competitors (meat markets with their own on-sight capabilities) but they often push people into the carry out (pig in a box) they do in their commercial smoke houses.
It seems the local Pig Guys skipped a generation around Northern IL. I'm coming to terms with and starting to accept being the "Pig Guy" instead of the Q dude.
Price wise I charge less for a whole pig roast than I do for multi-meat catered gigs. (Consider my hobby/business is a one-man show)
Handling, preparing, cooking multiple cuts and types of meats requires more time/focus/labor. When I do a whole pig roast I've only got one cut to handle and cook. Serving time, same thing - multiple cuts vs. one cut.
The more cuts of meat, types of meats, and sides, etc - the more labor is involved. If they want more than a one-man show can provide, I've got things lined up but costs go up considerably.
My experience in the past 2 years seems about par with alot of what I read on these forums, ie: seems to me the average gig is around 100 people. That works very well with a 100# whole roasting pig (which is a very readily available and typical size/weight for dressed whole roasters), keeps cooking time to around 12 to 14 hours with my MeadowCreek smoking at 230degrees.
Another benefit of doing whole roasting pigs? Slow and low smoking in my reverse flow is hard to screw up and whole pigs are hard to over cook. I've cooked in snow, subzero temps, heavy rains, high winds, and combinations of many of those. Every pig has been ready ahead of the mark, drippingly juicy, fall apart tender and usually not around long after.
I'm rather enjoying becoming the local Pig Guy and cooking other serious Q for competitions, family, and friends.