Direct Drive Vs. 25-49hp Motor?

Gentlemen:

I have question regarding equipment, it’s been years since I have been in the carpet cleaning business and a lot has changed. Currently I own a general contracting business (handyman services) with about 8 trucks. We have a full crew and I thought that at least one of the vans should be converted to clean carpets. (We have 20 years worth of clients) In any regard, the system I used in the past was a Butler and I have contacted them about their products. I have also been talking to a broker of several competitors. The big difference that I can see is that the Butler is a direct drive system and all the rest (ex. NIKE 745, POWERCLEAN, CHEMSPEC, ext.) Are powered by 25-50hp stand-alone engines. I asked the salesmen at Butler about the cost of running a V8 to power your blowers and pumps in addition to the consumption of fuel per hr. He suggested that I get online and go to a message board and ask you guys your opinion. The question is: what is a better / more efficient system? A slide in unit with a 25-50hp engine or a direct drive. Any advice would be very helpful.

Thanks in advance,

Dan