The ER-4 was my only other choice that I considered. I would not use a Mikrotik to easy to have bugs and hacks. Plus their code seems to work one way and if you use it a different way it has problems. I would not trust it.
That's very ironic. Cisco has quite literally a
magnitude more bugs and vulnerabilities than any Mikrotik device, some much more serious, including
very recent ones. This is especially the case for their
Small Business lines. Unlike Cisco, Mikrotik devices are externally secure by default. Customers have to intentionally weaken their configuration to have been exposed to any external vulnerability in the past decade, e.g. running remote management directly on the WAN. Even many consumer routers do not allow such unsecured configurations by default ...
No idea what you mean about the code. You cannot customize Cisco code and you cannot use any other code. You do it their way or no way. You cannot even use the command line in some Cisco Small Business routers, and for many other Cisco devices its command line or nothing. By contrast, Mikrotik RouterOS is 1:1 between GUI and command line in almost everything and both are always available, making it incredibly convenient as a power user or professional, across their entire portfolio. If you can use one RouterOS device, you can use any other, including running it as an OS on your PC.
If you really wanted to, you can load up open source on all non-Tile Mikrotik devices, afaik. They even formally support doing so with virtual machines called Metarouter on many of their devices, i.e. creating virtual routers in one physical device as if you had a PC running VMware. Try doing any of the above in Cisco Small Business routers, or any of their routers for Metarouter equivalent with an open source operating system.
Trust whoever you like, especially since you used to be a Cisco professional. Ask Snowden if he trusts Cisco devices! However, Mikrotik didn't become a top WISP provider for so long without being trusted.