CRM and ERP

Dear Experts:

Our company is into property development and builders, as of now we do not have CRM and ERP solutions i have been asked to look into this, hence approached salesforce.com it is per user basis charges and it works out to be huge amount also every year we have to pay same amount. hence thought of checking open source solutions hence with the help of experts exchange i got to know about opentaps the default package of the opentaps will not suit our business requirements hence put the query to opentaps they engaged the representative,  in turn representative did contact us and upon discussion the opentaps has to be customized as per our requirement hence we shared the scope and finally they have given the proposal and also customization duration time period is also okay for us, it is one time investment also every year support subscription it works to be far cheaper for us.
1. Iam still afraid to go with opentaps thinking what if it fails then i will be in trouble, please suggest me, can i go ahead on this if i get succeed in this then entire systems department will be valued and can expect good results from the management, please suggest.