Here is a relevant thread on the topic. It was a few pages back:
https://www.bikeforums.net/track-cyc...computers.html
I've used power meters on the track since 2010. And in 2009 I used a PowerTap head unit with no power, just speed and cadence. I've been watching this sector for a while. I've owned 3 track SRM kits over the years (even ditching power for a while (I still don't think it's needed for sprinting)).
My advice:
Save up and buy exactly what you want ONCE. Don't gamble on a power meter based on marketing brochures and websites. As Public Enemy says, "Don't believe the hype." Get real-world opinions. There is a LOT of hype in the bike power meter world. There even exists a wind-based power meter that is technically a power meter, but it's not what people expect.
There is no power meter that is perfect for both road and track (that I'm aware of).
Every power meter has compromises. Find them. This is where people get disappointed. Find out if the compromise that a PM offers is a deal-breaker for you.