first off congrats! they're a workhorse if they're maintained really well. have you had any flatbed printer experience before?? and what type of stuff do you guys predominantly run?
i would check the nozzle check, head lifespan, and have them print your files to get an idea of how it'll translate to your business. also definitely request any maintenance history it has had. as it only goes to 64" or around there, running full 4x8 sheets won't take too long, depending on quality mode. the r2r is not the greatest though, so if you already have a latex or eco sol currently id reccomend keeping it around. tracking issues among other things on the 1st gen keep it from excelling at roll-fed material. its great for short-runs, but i wouldn't hold your breath on long runs. overall print quality is pretty solid for what it is. express to outdoor plus is good for distance signage up to around 8 to 10 feet away and further, with very limited banding. indoor to max dpi is great for more detailed things that you really need up close and personal viewing. by no means should you be expecting art quality reproduction but it can do some pretty good work. if your used to running a roland, epson, or even hp latex, the quality will be a pretty steep drop off, but just keep in mind max resolution on the fb-x00 is 1200x600, but most of the work you'll run will be 600x300 in production modes or 600x600 for your indoor modes.
build quality is pretty solid, I'm still running a fb700 thats almost 7 years old. while we have replaced a few major parts over the years, as long as you can maintain a service contract with hp (along with a very conscientious operator, I've known some who just throw sheets in and eat heads so make sure you have someone stay on top of it) , when things pop up, it won't be the end of the world $-wise.
all in all, id recommend it as long as all the nozzle checks are in order, maintenance history is good, and can get a service contract. lotta boxes to check but its a solid buy, especially if you have the workload to feed it. any more questions, ill answer to the best of my ability! good luck!!!