Hi, here is a few ideas for you. A few things to think about here depending on what issue you really try to solved.
First a good ISP after you actually reach them have built redundancy on their network, so unless you try a cheap one, then you should be fine there. Then what could go wrong? Well plenty yes, but less take them. - Power, well UPS, if UPS runs out, two ISP will do nothing. - single router blow up, same thing. So, you designed it with two as you put it, great. - Local loop, last mile, well if it get cut, then it's cut and needs to be fix. So two line needs to come in. One solution may be as simple as getting these two lines form the same ISP and have them merge together. Like if you use T1 for example, then they could be bundle together via PPP and allow you to use the full capacity of both and if one goes down, you still have the first one and nothing is lost, no traffic is lost and all continue, just slower. You might be able to get it cheaper if both from the same ISP as well and they would need to be provision on the same router on their end anyway to merge them. This way, you don't need BGP, you get backup as you want to get, on line goes dead, you still have the second one. But then, you don't have your IP problem and believe me, getting any IP's from ARIN these days is pretty darn hard! Unless you want IPvShit, then you will be giving them right away. They change their policy last month if my memory is good and you sure can get it for your site, but then, you hell open a truck load of other issues however. This combine lines also address your requirement of balancing your traffic, but in this case, you don't need anything special, it works no problem. I don't know how things are in Chicago, but if it is like hereon the east coast, looks like Verizon enjoy playing with wire in central office and disconnect lines at random. I don't really think they are doing that, but sure hell look like it however as problem are always with the local loop! So, this may well works for you and get you want you want to do. Just a thought anyway for your consideration that may address your needs in a different way. Best, Daniel