To be completely honest if you buy another TM800 you will be wasting your money. Its highly unlikely that any more images will ever be released for this box, its also only a matter of time before the download server for the TM800 images is switched off too.
I know its nice to work with a box you are familiar with, but to be totally honest if you can use a TM800 you can use any other Enigma 2 box, they all operate in more or less the same way. I like my TM800 but there's no way i would buy another one when there are better boxes on the market for more or less the same price.
At the end of the day its your choice which box you buy, we can only try and guide you when deciding which box to buy.
Nano