As far as being able "to scan 400 scanlists", you can't there are only 200 scanlists, which can be assigned to one or more scanlists. And, these scanlist can be assigned to one or more scanset. There is not 200 scanlist for each scanset, there is only the one set of 200 scanlists.
RDGDigital is correct about nomenclature being confused, but should examine the section I quoted here. He's right about everything else. Tvengr is also right in what he's saying. N1GAW and N8IAA are both confusing Scan Sets with V-Scanners. Let me give it a try:
1 - When you turn on your TRX-1, there are 200 Scanlists available and you can scan them or skip them in any combination. Each scanlist can have has many or as few objects (frequencies or talkgroups) as you care to assign to it. And you can assign a single object to more than one scanlist if you like.
2 - One of those scanlists will be the 'Default' scanlist--which is the scanlist to which any new frequency you enter is assigned unless you indicate otherwise. The usual default Scanlist is Scanlist #1. You can set any of the 200 scanlists to be the 'Default'.
3 - IF YOU WISH (i.e. this is optional), you can assign any of your 200 scanlists to one of 20 Scan Sets. In the initial setup of your radio ALL scanlists are in Scan Set #1, and you can leave it at that if you wish. A Scan Set may include as many or as few Scanlists as you want, and you can include the same Scanlist in more than one Scan Set. Scan Sets are there so that IF YOU WANT, you can toggle multiple scanlists in and out of the scan as a group. You don't have to use them if you find them confusing.
NOTE THAT ITEMS 1, 2 & 3 are all in your scanner when you turn it on--in one single programming (V-Scanner).
4 - Your scanner can have up to 200 different complete configurations or personalities stored, and these are called "V-Scanners". Think of these as files on your memory card that you have to call up. Each of these 200 personalities contains everything that I described in items 1, 2 & 3 and you can customize them any way you want. To be clear, each V-Scanner has 200 Scanlists which can be sorted into up to 20 Scan Sets.
5 - You cannot use more than one V-Scanner at a time. Think of each V-Scanner as completely reconfiguring your radio. (because that's exactly what it is) You don't have to use multiple V-Scanners. Your radio has a default one that it's already using unless you change it.
To conclude the hierarchy is:
V-Scanner - A complete programming of the radio, each giving you 200 available scanlists which can be distributed (at your option) among 20 different scan sets. Your main V-Scanner is called CDAT, and that's probably what you'll use if you don't wish to have more than one V-Scanner. There are 200 V-Scanners available for you to program, but you can use only one at a time. (Think of the V-Scanner as the Folder, with up to 200 sheets (scanlists) inside. They could be organized with up to 20 dividers (Scan Sets) which keep related sheets (Scanlists) together.
Scan Set - A group of scanlists that you have decided you'd like to access or turn off as a unit. You can have up to 20 groups. If not interested in organizing in this way, your radio is set to have Scan Set 1 active, and it contains all 200 scanlists. All Scan Sets are available to you at all times, within a given V-Scanner.
Scanlist - A group of objects (frequencies or talkgroups) which will be scanned together. There are 200 available to you in each V-Scanner. You can toggle each Scanlist in and out of the scan individually, and all 200 are available to you at all times in any combination within a given V-Scanner.
If any of this confuses you, I strongly recommend that you not alter Scan Set #1, because it allow you access to all your scanlists.
Depending on how you operate, and how far you travel, you may not need to deal with Scan Sets or V-Scanners.