Mortgage Broker vs Credit Union

[Manco Snead]

Greetings all,

Newer investor here (own one duplex with good equity) moving toward buying a second multi-family, likely via 5% loan, cash-out refi, or HELOC. Trying to understand a few concepts here:

1. My current duplex is financed through my credit union and I've always been happy with them. For a new loan to finance an additional multifamily what are your thoughts on credit unions vs mortgage brokers? I've only ever used my credit union and like the idea of continuity and sticking with something that works, but I understand many people like working with mortgage brokers. 

2. Perhaps the obvious is escaping me on this question: If I choose to refinance or do a HELOC on my currently owed duplex I would be able to do that only through my credit union through whom I have the loan, correct? I could not do a refi or HELOC through someone else, i.e. mortgage broker, other bank etc, correct?

Much thanks.