Goron,
Sorry, I too made the assumption that you had bought new and invested £15,000 - £20,000+ on your machine, vehicle, etc.
However if you got it for a fraction of that and it's in good conditon, then well done. we are mere portable users at the moment, but some of the commercials we do could not be done with a TM due to security access, etc.
You will probably find that quite a few TM users have a portable as a back up anyway. I am going the other way, I am looking out for a TM as an option for my business growth, therefore going down to the NEC next month to see what's on offer.
Once again, good luck, check your PM's