Everything should work the exact same, it’s a fully functional plug and play replacement for sid chips. I’ve never used the external input on a sid station but you aren’t changing the fundamentals of your synth, just the sound source and it’s designed to replicate the original sound source so sonically it’s very close to the original. Being that it’s emulative you can even set it up to sound like an 8580 but I prefer the sound of the 6581 just because it’s a little more sizzly, like that “pew pew, lasers” sound, I don’t know how else to describe it, more nostalgic for me.
As far as functionality, I don’t think your sid station will know the difference, but if possible I’d encourage you to try and reseat the chip and if possible meet up with someone who has a sid synth or a c64 so you can verify your chip is bad, otherwise if you buy armsid and your synth still needs work I don’t want you to feel frustrated about spending money and waiting for a part you didn’t need. Otherwise, you could still preserve your chip and use an emulative chip instead just for the longevity of use. I already said it, but I really like armsid and it was easy to get a hold of the guy that makes them and get questions answered so it felt like I didn’t have much to worry about going forward.
Anyways the filters and everything are fully functional on my synth which has armsid chips in it so I can’t see any reason you would have trouble still using the filter input of the sid station.