A birdie suggested Kiloview for a decoding appliance, but I can not confirm if it works at this time (yet to get hands on one). I imagine many companies will be updating their hardware H.264 encoders and decoders to support SRT. Some might only need firmware updates to do so, I suggest reaching out to the manufacturer of your current decoder and asking them for SRT Support.

In addition to Kiloview (I bought an E2 encoder works well, before I knew I could upgrade my Digicast encoders). Digicast (http://www.digicast.cn/en/) support SRT Encoding H.264 and H.265. I've been testing firmware updates (not sure if they are shipping the firmware yet, they sent me the firmware via Skype). I reached out prior to buying a Kiloview E2. They got back to me after the E2 arrived, I'm happy no fee for the upgrade to support SRT on my older equipment. I don't regret having another brand, helps having two different brand options in your kit.

I'm yet to try an SRT decoder black box from any company, but the D300 looks interesting to me (Previously been using Raspberry PI as decoder/player for ultra low latency RMTP). I might wait until someone else tries it. I'm not worried about 50i, I a progressive person most of the time, being more a computer screen caster :)

Yet to see anyone do SRT decoding on an Raspberry PI (might not be possible), but it was an AWESOME low latency RTMP Player. Easy to replace, uses very little power, with the right image on the SD Card was a reliable box to send to someone to play a video stream. It used very little CPU to decode as well, since it's graphics chip did most of the work. I was using PI 2.

Maybe someone will get a PI 4 doing SRT display, that would be nice.