My father used to own two of them. They were good while the satellite service lasted. They made for good OTA tuners after its demise, but they were never able download guide data or scan in additional channels. They're only good for the area they're mapped to for OTA purposes. I loved the Voom satellite service, but unfortunately, it was too much ahead of its time. I'd really love to have Monsters HD back again.
As for your question about other models available, my understanding is that they only had one model during their short existence.