As mentioned they are different type receivers in a lot of respects, the 5402 is what you'd expect from a classic Technomate non-Linux receiver, it works great once patached as a CCcam + Newcamd client, it's got a built in fan and RF out, YouTube player and free xxx video stream over the internet(accessed by a secret code/menu) and will work no problem with a motorised dish and is basically all menu driven with setup, it's as easy as they come (naturally they all need some kind of setup!), PVR functions are by way of an external USB drive.
The TM800 is a little different, in a lot of respects you can almost forget it's a Technomate receiver because it's Enigma2 based and so operates and functions a lot like other Enigma2 receivers, so don't expect the classic Technomate style menus if that's what you're used to, but the good news is it has loads of support for all the usual channel list and updates, on the third party image support it's not fantastic at the moment, you have the iQ team which are the main ones and then others based off this, there are a few things that don't work at the moment such as timeshift and streaming from the webinterface and it's not ideally suited at the moment for an internal drive (at least not without adapters) so like the 5402 I would suggest you go with an external USB drive for PVR functions and more. It will also run CCcam no problem and an addon for a good 7 day EPG for major Euro providers.
It depends what type of user you are, if you want something that's easy to setup and manage then the 5402 would be the one, if you like to get a bit more technical then the TM800, but at the same time if you are considering the TM800 then do yourself a favor and check out the QBox HD Mini and VU+ SOLO at the same time, for the same or not much more money than a TM800 you can have a couple of boxes that right now work and are supported a lot better
