Ok here I go on a pet peeve topic again:
PLEASE don't put too much store in a farm name/prefix horse for starters. For example, using my own farm name (not that I'm a great example of a "bloodline" w/my small numbers): There is a HUGE difference between my mare Raftered Hearts Raven Star and one of my first born horses here that I did not even technically breed, but put my "farm name on" anyway, RH Icy Wind (a poorly conformed, but sweet colt I sold as a pet).
Still my farm name, but vastly different quality. So you can put "GREAT FARM NAME" prefix on any horse whether you bred it or not (or the farm could, heck you could, too, if it's not reserved) and it's not the same quality because even the best farms produced horses that were not intended for breeding nor the best example of their program.
You go for example into the "Bond" name and go from Bond Tiny Tim to Bond Showboy. Related? Yes...but HUGE range in quality and type. I don't think anyone today would, in their right mind buy a direct son of Tiny Tim to have as their brood stock, but Showboy..yep.
All in all it comes down to NOT getting sold on a pedigree. Unless it's proven, it's also not always worth the paper it's printed on.
First and foremost is to purchase the best quality horse you can afford and often times that is more than you think it would be, but your investment will be in time and research efforts. Find good breeders that stand behind what they sell, and don't expect them to sell their top quality breeding prospects for pennies because they are worth far more. I laugh (though politely!) when people want me to sell my colt that I want to sell/show as a gelding to them for the same or less than I want for him as a gelding. Why do people want to buy a breeding prospect for pennies compared to what a good quality gelding goes for?
Once you find a breeder/seller that would understand what you're looking for and work with you, you will find you can make better decisions on what YOU want. Go to shows and visit with the people who are winning top placings and find out the bloodlines/background of the horses you like. Compare them with others of the same or similar breeding. You will start to notice what makes a good horse a good horse and hopefully then be able to find it for your self.
Buying young stock as speculation for breeding can go wrong any number of ways and that can be infertility, health issues that show up as they mature (such as a bite going way off, a stifle issue, undescended testicle, etc. just a few of the more common ones). Get guarantees on height, bite, fertility, etc. and don't expect it to be cheap for these, but if you buy good stock, the breeder should be reasonably sure they will suit your purpose.
I can say that of the bloodlines I have read so far, there are poor examples I have seen of every one of their "bloodline" though many of them do have a common quality and type and watch for that, also when you shop try to get the breeder to share with you either in person visits w/sire and dam, or good photos of all (and bite, etc.). These are important factors for if you don't give them the attention they are due, you may end up with a terribly disheartening problem. I know many of us have been there and done that...so speaking from experience myself as far as not getting what you hoped in purchasing breeding stock.
The longer I go in raising minis, the more I appreciate what some of these people have put into researching a good breeding program and if you notice, the best ones are always changing a little, and modifying for the better, IMO.
Use your bloodline question to begin your research, but don't be scared off of the unknown horse, just be sure to do your homework as far as ancestors and paperwork.
Sorry if this is long, I just hope to head off problems I myself encountered as I stumbled along in the dark through my own attempts to refine my herd.
Liz M.