Day four in Paris, and a question that has not been answered yet is whether, as Bombardier and Embraer believe, there is a market for their new aircraft at the airlines now ordering Airbus A320NEOs and Boeing 737MAXs by the hundreds.

It is less of an issue for Embraer, which launched its 88-132-seat E-Jet E2 family here on Monday with 365 orders and other commitments anchored by its traditional regional-airline customer base. But it is crucial for Bombardier, which is trying to create a niche for its 110-160-seat CSeries and has not announced any orders here, so far.

There have, however, been orders for Airbus and Boeing - 223 commitments so far for the NEO and 203 for the MAX. And as the show enters its fourth day the order taking has not slowed appreciably – nor is it likely to soon after Boeing announced here that it has brought forward first delivery of the 737-8 by six months, to barely 18 months behind the rival A320NEO.

When Embraer unveiled the E-Jet E2 family on day one of the show it talked of its ability to complement the larger narrowbodies and allow airlines to “right-size” their fleets by also operating smaller aircraft with lower costs on thinner or newer routes. The E195-E2’s cost per seat is 5% lower than the A319NEO’s, the company says, and its trip costs are 25% lower.

It is a message Bombardier has been preaching as it tries to sell the CSeries, pointing out the CS300 is 12,000 lb. lighter than the A319NEO for similar seating capacity. And while the cost per seat-mile of the CS300 with 160 seats is about the same as the A320NEO with 180 seats, its trip cost per aircraft-mile is more than 20% less, allowing it to fly the same routes more profitably at off-peak times.

But Easyjet’s decision, announced here on day two, to buy A320NEOs after also evaluating the CS300 as well as the 737MAX would seem to suggest the message is not getting through – although Bombardier believes the door is still open to the smaller CSeries at the European low-cost carrier and elsewhere.

It is a bit like the supermaneuverability demonstrated here in Paris by the Sukhoi Su-35S fighter and the stealth promised by the Lockheed Martin F-35, which is not here to defend itself. The Russians believe high agility in low-speed, close-range combat remains important. The U.S. believes sensors and stealth will win the day.

Which is the most useful, winning the knife fight in a phone booth or avoiding the altercation altogether? Bombardier finds itself sharing a phone booth with a heavily armed Airbus and Boeing, while Embraer stands just outside the open door, watching, with no compelling need to step inside. Only time will tell which has picked the winning position.

And here is another choice of positions to think about. Lockheed Martin says it is considering developing a civil variant of the C-130J Hercules military airlifter to replace around 70 older L-100s now with civilian operators. Embraer is developing the KC-390 to compete with the C-130J, and the aircraft will be civil-certificated as part of its development program, but CEO Frederico Curado tells Aviation Week he does not see a civil market for such a rugged, robust machine. Who is right? Time will tell.

Here in Paris, the fourth day promises to be entertaining if perhaps not eventful, as John Leahy, Airbus’s chief operating officer for customers, and ATR CEO Filippo Bagnato address the press. Leahy is always outspoken and, with Bagnato at the helm, ATR is enjoying a boom in regional-turboprop sales – announcing orders and options for another 110 aircraft so far at the show.