Just my two cents... Make sure you're comfortable around ANY horse of any size. I've ridden horses my entire life and would consider myself advanced at least in casual riding. I've trained horses from the ground up and broke a couple that were older. I can sit through a buck and show a horse who's boss. So, when I decided to get a second horse and a beautiful all-black percheron gelding came up for a good price that just needed some re-training, I went out intending on bringing that horse home.
Didn't happen. Just a little bit of skittish-ness on those plate-sized feet was enough to make me feel nervous, and I knew that little bit of nervousness would turn in to a lot of heartache down the road since I didn't feel that I had the confidence to work with him. Sad day :( But, that's ok, because I got into endurance, where my new Arab was much more fitting.
Since then, the rose-colored glasses have come off more and I realized it was a blessing in disguise that he didn't work out for me, more than just not being suited to endurance. Not to mention the inherent risk of having a HUGE animal (all horses included, but even mores with drafts), there were a few key points I hadn't considered:
1) Feed - with the price of hay, I'm glad I don't have to feed a draft.
2) Tack - I have a hard enough time finding the right tack for my boy as it is, and he's "typical" sized. But I have to work to find things that are just right as any horse person does/should. If I were restricted by the few things carried for drafts, I don't know what I'd do.
3) Logistics - You have to have a pretty good truck and trailer for a horse that size. I doubt the typical low budget F-150 and two-horse straight load would not get the job done.
4) Flexibility - I'm always expanding and wanting to try new things. I wanted to get into endurance, something that most horses (and I've even seen a few ponies!) can do to some extent, but a draft wouldn't have been a wise choice. Sure, some can do it, but I would hate to have to manage that thing. Ultimately, for the things I'm interested in doing (either now or maybe trying someday down the road), a lighter breed would have been more fitting. (That being said, drafts can do low-level jumps!). I think I would have been much more limited in my choices had I bought that horse.
5) And of course, the simple idea of working with the horse. Remember, you're not the only one that has to - so does your vet, your BO, your farrier, etc. And though they will likely have experience with them, it's ultimately your responsibility to make sure you can train and correct anything that goes wrong. The horse is only as good as it's handler, so if you have holes in what you are capable of, those will be multiplied by horse and every pound he's got.
My point is that there's a lot more to be considered in buying a horse than just the horse itself. But, in the end, if you absolutely love the horse and are willing and able to work with these things, then go get your draft ;)