MTB is easier on the amount of training required, but a lot of MTB bikers are succesfull when they switch to road racing, it helps that you are going up and down all the time so you kind of develop a good anaerobic capacity,
isn't it the Itera Cross ? or maybe it has gone out of their catalogue,
first of all i think it is overpriced (the Itera Cross) for what i see in their website,
anyway if the bike is in good condition you can sell it for a couple or three hundred euro less than the original price,
do you have a link to your website for us to see ?
if you have a personal page on facebook you can also add a facebook page dedicated to your bike shop, they have the option for business pages, then you would insert the facebook logo on your website linked to that facebook page that you are gonna create, so your facebook bike shop account will function the same way as your personal account, people will interact there, upload pictures, etc all for free, so your internet...
and no worries for untrue rims and broken spokes ! with disc brakes,
( although you do need to service the wheel eventually, it wont ruin your ride )
p.s. Avid BB7 mechanical disc brakes are great, easier to setup and to maintain than hydraulics