Hi,
I’m making a board that I normally use 0.5 mm hole vias as my standard size but I’m getting a little tight on space and would like to use 0.3 mm hole vias instead. While the specs on their website say that they can do down to 0.3 mm holes, I’m wondering if it’s likely that I’m going to have problems with this? I’ve boards made by them before that use 0.3 mm holes but none where a connection relied on a single via being correctly plate through, I’ve only used them for stitching and thermal purposes. 
What I can say about the boards I do have with small vias is that they seem without error but it’s hard to test connectivity of a single via when it’s part of a net with many others. If it’s unlikely to be a problem, I’m thinking I might as well go down in via size all over the board.