On the cost of producing a 2-sided stysem: that wouldn't be double because there's marginal costs and fixed costs of production. The latter include development costs, rents on the building, salary, shipping receiving, marketing, etc. The second side would add only marginal costs, except perhaps if there were reduced sales as a result. Electronics are amazingly cheap.I'm interested in how good their cadence data are on rough roads, with accelerations, and on space stations.