The Signo won't be out for a few more weeks, so it's all still speculation.
As for the Como, there have been mixed reviews, but I love it and we will be getting 2. Personally, I was looking for a seat with a tall shell, to keep my tall 2yo RF longer. The seat is very very wide, I think an inch wider than the big Britax convertibles, so if you have to fit 3 across it might be tricky/impossible unless you have a big car. We don't need to fit 3 across, since we have a minivan, so the size didn't matter.
The 35 lb weight limit is great, but I am disappointed that it doesn't have a RF tether.