I am seriously considering a company where the owners keep talking up how strong of relationships they have with their customers. They've been in business for 40+ years and have lots of repeat business (no recurring contracts though).

I am trying to figure out the best ways to assess the risk of customer churn if another owner were to come on board (particularly someone like me, without experience in this construction-tangential space). I'd like to do this risk assessment pre-LOI since I think it has a pretty big probability of being an issue.

Two relevant pieces of information for this company:
- Customer concentration is borderline - top 5 customers make up 22-27% of revenue depending on the year
- The business has a lot of repeat business that recurs every 1-4 years but no long-term contracts (a lot of handshake agreements)

What outcomes would you need to see w.r.t typical customer relationships to be comfortable? I can't come up with any concrete go/no-go decisionmaking criteria... without that, there's really no point in going through the exercise at all.

Does anyone have tips on go/no-go criteria as it relates to the customer/owner relationship?