Using preparation consultant ?

Hi guys,
I am working in IT and telecoms industry in Singapore for 11 years without MBA. I am applying to consulting firms (MBB and rest) in Indonesian offices where I am from. Consulting is hot in Indonesia and other SEA countries now.

I studied from Cosentino, Victor Cheng (both are not good I think) and Ohrvall's (better than the other 2) books, and practiced with people for about 30 cases and now I feel fine though sometimes I make mistakes in cases, just need to be more careful I guess.

I also have been connecting with partners and consultants in my target firms (MBB, ATK, Deloitte, S&, RB) and let them review my resume and I got positive responses from most of them.

I was dinged by BCG after first round and the feedback was I was slow in the case, and my recommendation sounds too "engineering". It needed to be richer, he said. I was nervous in the case after a difficult test (there was a 45-min test before 45-min interview). The interviewer was 10 minutes late and asked only 2 short fit questions and moved to the case.

Now I am considering to hire a preparation consultant, I am considering firmsconsulting(dot)com or managementconsulted(dot)com.

Do you guys think those prep consultants are useful or are they bullshit? If they are useful, which one is good?

Thanks a lot.