Correct, performance-wise, there is no difference given the same switch, and similar construction.
The real differences are subtle and down to user preference and or styling and you can even do a lot with reprograming in software, ignoring the keyboard firmware.
When I built my Filco the idea was to replicate a KMAC but with easy to find, easier to replace parts in case something failed. Not sure I saved a whole lot of money, but I can replace anything in it it a whole lot easier. Is it as cool? Probably not to most, but at the same time, it's one of a kind and works amazingly well. You already have a good board, there's really not a lot of room to go up from there other than specific features. It's not going to be revolutionary or last longer, you will just get a more "premium" feel.
I put premium in quotes for a reason, there is quite an argument to be made that plastic cases are better. Besides the whole perception of it being better (such a pretty Iphone you have, shame you need a crappy rubber case to protect it!), aluminum has some serious downsides people don't often mention. It's cold to the touch, it can damage your desk, and believe it or not, shock the sh*t out of you if there is a lot of static electricity around. I have 2 aluminum keyboards, and while I like them, they are not any better at typing than the others, they just look nicer and have a heavy price tag.