Scott Kay's entire lineup is now offered in Palladium, he is one of the industry's biggest advocates for the metal. Several (but not many) forward-thinking jewelers have changed their entire bridal showcase from 14K/18K white gold into 950 palladium because of the added benefit of never having high wear jewelry such as bridal turn yellow and need rhodium plating which both saves them money and keeps their customers happy. I think this trend will continue.
Personally I love the metal, I don't work with any designers that don't have the patience or expertise to work in palladium. It will take time to educate the public etc so they don't think palladium is something cheap like titanium, it's still an expensive metal and I think it has a lot of catching up to do with platinum both in industrial use and in the jewelry industry so the price relative to platinum will go up in my opinion.
But if I were you I'd stick with platinum to match your other ring, because that way if you ever need repair work, or sizing, or whatever, you can take it to any jeweler and they'll have no problems working on it. There are many goldsmiths out there are who are inexperienced working with high purity palladium alloys or they don't have the wire or sheet needed to make repairs. There is an art to casting platinum, and palladium is just as fussy, if it's not cast right you could have porosity or other issues and the temperature to melt them is much higher then karat gold, so the skill level required to work with palladium and platinum is higher. Anyone can cast gold alloys, those that knock platinum or palladium either don't have the experience with it, or just don't like the hassles that come with working with it.
but apparently it expands rapidly when exposed to hydrodgen as it can absorb 900x it's weight of it.
Yes, that's why it's used in automotible catalytic converters, just like platinum. It reduces the hydrocarbon emissions from your car's exhaust. I used to drive a Honda Insight (the hybrid) to commute with and I had to replace the catalytic converter and it cost me $1200!! That's because it was made with a LOT of platinum to bring the emissions down very low. Many hydrogen fuel cells that are made for the next generation hydrogen vehicles use a lot of palladium to store the gas. Unlike gold, platinum and palladium uses are more industrial then jewelry and they're both used in many similar applications because they have very similar properties. As the world industrializes more and more (especially in China and India) and the world tightens down on emissions and hydrogen fuel cells become more used, you'll see both platinum and palladium demand increase causing prices to go higher.
