Earlier this year I bought a Shoei Glamster full-face helmet from Urban Rider in London. It's CE approved but not DOT approved, which as far as I can tell means that if I crash while using it on holiday in the Alps, I'll be fine, but that I'll get really hurt if I fly off here in California. I wanted it because my other Shoei helmet just seemed a little too big and serious for a ride to the beer store, and despite my fervent denials, I guess I care a little bit about what other people think since I just didn't want to be Commander Matchy-Match on a white scooter with a white helmet. On their customs declaration they called it a "Novelty Collector's Fiberglass Helmet".
The Glamster (unbearable name)) is a lot smaller than the RF-1400 and really does feel a bit like a novelty helmet, but hey, it's a Shoei and it's CE approved so I have faith in it. It never occurred to me that it would actually fit under the seat on a Vespa 150, especially the North American one with the big indentation to accommodate the EVAP crap. But today, for some unknown reason, I tried it and was pleasantly surprised as it slipped right in. So if you want a full-face helmet that fits under the seat on a modern Primavera, go Glamster, just don't tell anyone what it's called.