Do seriously examine what benefits you wish to gain from a large jump to such dedicated equipment. If all you want to do is make a few knives and heat treat them well, a good furnace will be just as good. If you want to do longer blades, richer alloys, or have very specific heat treat requirements salt baths my be worth it if you are gearing up to get pretty serious about professional knifemaking. Short of this I am not sure the risks, expense and hassles outweigh the benefits.
Salt baths will not make better knives, only a skilled and practiced knifemaker can make better knives, in fact what salt baths and other very powerful equipment can do is make errors much bigger and much quicker, if you are not ready for what they are good for.
I say this as a maker who has been working with salts longer than the majority of folks on this board. For a while I was really so geeked about them that I recommended them for everybody, but now that I have been working with them for enough years for them to just be another tool, I am not as quick to push other makers in the direction of some very expensive and rather dangerous equipment unless they have specific needs that can be addressed by it. The salts will also need to be kept balanced and neutral or they will do things to your blades that will make you forge look pretty good again.
If you decide you need things that salts have to offer, go with the high temp first. I can often judge if a person is really ready for salts if they realize this, if they want the low temp first, they are too caught up in salt bath hype to really grasp the step they are taking. Also have a supply of proper salts lined up ahead of time, it would be a shame if you had all that equipment and no salts to put in it. Another red flag is if I get a question along the lines of "O.K. I have my salt baths built, now what are the salts used, will sidewalk melt, or Morton salt work?" this will get silence from me as I will not be able to delete that e-mail address fast enough.
I am not trying to discourage you, just trying to help you go into the investment with your eyes wide open.
