Hey Joel! We actually tested the NLSS Decoder a couple years back and found it worked pretty well as a split screen decoder. As long as you aren't looking for full blown VMS client functionality, it works well.
There's at least 2 newer options worth considering, see: HD Decoder / Thin Clients
IPVMU Certified | 11/26/16 01:43am
I've used the DW Spot monitor mentioned in the thread John mentioned for two different installs. It is limited to four views but works well. The limitation I initially found was that it said it supported cameras up to 5MP, but it didn't support 4MP. The cameras that were displayed on the unit were 1080P so that wasn't a problem. DW tech support initially told me it was supported until I corrected them and they said they would change their documentation. I haven't tried a 4MP since then but I don't believe a firmware update changed that issue and if it did, then their documentation isn't really accurate or clear enough in opinion.
If it's only for four cameras the NLSS seems expensive. The interface on the NLSS seems nicer though and there seems to be more features available on the NLSS.
IPVMU Certified | 11/27/16 03:24am
After trying several different models, I ended up using ACTi ECD-1000 decoders for several projects. These can handle up to 16 channels HD but you can configure it to any combination up to that. Deployed them throughout a large industrial facility control rooms.