I purchased the original Slingbox when it first came out and I have been very pleased with it hooked up to one of my ReplayTV PVRs.
Yesterday, I wanted to watch it on my iPad, so I went to the Sling web page, and it said no, please buy the $15 app, so I did, even though I had a mobile Slingplayer app on one of my retired iPaqs.
After buying the iPad app, I find it doesn't work with my original Slingbox, so today I spend $160 at my local Best Buy and add a M1 to another ReplayTV. Setup for audio & video is pretty easy, but I have been going through every ReplayTV and Sonic Blue remote to try to get full functionality and have been unsuccessful. The Channel Guide comes up with the Replay Guide button and the Replay Guide cannot be accessed at all. I don't think the Jump buttons are working either, but haven't been fully focused on that yet.