I disagree on a case this size.
If the group was 1,600 lives then I would agree with you.
The group may want to build a relationship with the broker. They also might need a lot of hand holding and a extremely high level of customer service. A large agency might not give that level of service.
A broker could look at Self Funding the case with a TPA to assist with a hand holding type group. An ASO plan would be able to deliver much higher discounts than a TPA but no hand holding.
This size case should have local working on it.
I don't like ASO or TPA for that size group but don't habitually distinguish between the 2. Yes, the majors have much better discounts & that is a selling point every time I run into a TPA. Also used to be a proponent of audits to see how well claims were being paid according to contract.
Seen too many without SL renewed or a health condition carved out. Also see my example of Medicare claim getting dumped onto the group. Then there was the cut & sew that was going belly up, changed to fully insured & had a hard time getting the run out paid.
People seem to think that they're running with the big dogs just because they have 100 people collecting a pay check. When I crunch the numbers, even approaching 1000 members, claims are only statistically about 65% credible.
I've had groups in other states and made the trip a couple of times/yr. Kept them for years until they were merged or sold.
If you do your job, there shouldn't be any problems that the employer has to deal with.