I have no experience with Brother MFUs, but I have some experience with Brother printers and with Brother network scanners. And I like them. So, your choice might be a good option if you are willing to do some extra work when processing your scans and when feeding different kinds of paper into the MFU.
A lot of the price of a good document scanner stems from its software and its technology when detecting paper sizes, page orientation, unwanted same time multi-feeding and so on.
There is a solution that is even cheaper: your iPhone with a good scanning app. I am not kidding. It really is a good option if done right.
I use Scanner Pro especially when I have my ix500 not available to me and it works just great:
I have it set up to scan in black and white and enabled compression. It detects new pages and scans them automatically if you choose to do so. It does OCR, you can use automation and even Siri shortcuts to process scans.
If you put your paper on a well-lit surface and maybe your iPhone on a stand above the paper you will get results that are very good (you can buy stuff, but with a little DIY stand you might even get better results). And even without the stand, you will get good results.