I had never heard of Remus Uomo before, so I just checked out their stuff online. I like! They also have some pairing suggestions when you're looking at an individual piece, which is nice (although wearing dark denim jeans with a dark denim shirt seems a bit...denimy to me when they are both the same color). I can't find any size information though (torso and sleeve length for a M/L). Do you see that anywhere?
Outfits that are for smart casual are actually not that pricey. You can actually go online and look for catalogs there.
There is always the option of a Portifino cuff to make a Formal shirt a little more fancy. Customer Shirt makers like Lewis & Taylor offer them if you ask