The motion is better than the GW60, the next model will be wireless and totally waterproof. but there are a few production delays at the moment.
I'd go with your last option, a small armband. Paqua made a key holder armband I think the watch would fit but I haven't seen any around for a while.
www.paqua.com.au/Product Details
Description

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PAQUAkey : the answer to your prayers! No more leaving your key on your tyre, or tied to you boardies when you go for a surf. Designed to house most current car keys, with in-built chips, or electronic remotes. Submersible to 2m - either use the supplied leg-rope attachment, or wear on your arm or leg...OR take the strap off, and put it straight in your pocket - water-tight, your keys are safe inside the awesome PAQUAkey. >>> click here for enquiries <<<
Dimensions:
W: 65mm x H: 100mm
RRP:
$39.99