I can’t find this specifically addressed so I’m asking it here. If I’m going to use the X2D for printing primarily with the left nozzle and using the right nozzle for support filament, and I just need run out protection for the primary nozzle, then can I use two HT boxes hooked to a filament track switch just for automatic run out protection on the primary nozzle while the secondary right nozzle is connected to its own HT box? I don’t need the multi colors that two AMS’s offer as well as taking up more space, being more expensive and not handling the high temperature drying. 3 HT boxes utilizing the track switch for the left nozzle only and connected to two of the boxes, seems to make a lot of sense to me… if this configuration will work.
Surely financially it makes sense to buy the combo and 1 HT, no FTS.
This will allow all colours, or same colours stocked and dried etc. The single HT would be as you depicted. You would then have two driers and loads of options in the future as you develop.
I believe the HT , being a powered unit, would notify on run out.
And if you want to stay with 2x AMS HT: In your scenario you don’t need the Filament track switch at all. just use the 4-in-1 adapter to connect two AMS HT to one buffer input / nozzle
All my Google inquiries are claiming that you need the filament track switch with my two HT boxes feeding one nozzle scenario. It is true that 1 AMS and 1HT would accomplish the same thing without needing the filament track switch but would only allow high temperature drying for one spool. I wish Bambu could highlight all the different scenarios possible in diagrams. I don’t think there are that many… then maybe most people aren’t as confused as I am. 
The FTS has the single purpose to dynamically switch two inputs between the two nozzles. It doesn’t care, how many AMS are connected to each input. Also the type of AMS is completely irrelevant.
If you don’t need dynamic choice to feed filament from one AMS to both, left and right nozzle, then you don’t need the FTS. Can you direct us to the resources saying otherwise? Anyway, how would you connect the 3 AMS HT the the 2 inputs of the FTS. Just skip the FTS and connect them directly to the two buffer inputs.
But I fully support @Mrburns 's advice to go with AMS 2 + AMS HT. I don’t have the price difference at hand between solo and combo version. But if you factor in the additional cost for the FTS, then 2x AMS HT certainly costs more than 1 AMS 2.
You might not see the benefit right now of an AMS 2, but once you have used it, you don’t want to go back.
And I’m not talking about multicolor prints. The convenience of having different materials or colors loaded ready to print in a dry enclosure is really huge. I rarely print multicolor and even then no more than 2. Yet, I bought a second AMS 2 just because a single AMS didn’t have enough slots to hold the spools that I regularly use. So now I have 2x AMS2 + 1x AMS HT on my X1C.
The AMS 2 also has an advantage over the HT: It has far more open space to fit some dessicant containers for keeping humidity low over longer times.
The only benefit of a second HT that I can see is less space required. If you aren’t super tight on space, really go for HT + 2pro.
Do you already have any of the machines?
You mentioned 2x high temperature drying. Can you explain what you have in mind?
Just as an example, here is my workflow:
As mentioned, all filaments that I use often have their fixed slots in the 2 AMS2.
Most of the time, the AMS HT is empty. When I get new filament, I use the HT for drying, then I either store it in a vacuum bag or box with dessicant or it goes directly to one of the AMS2. Filament that I only print occasionally goes into the HT and after the print back into its bag. I never use the AMS2 for drying, because I would have to unload the other filament. Don’t want to stress already dry filament.
Translating to your situation, I would connect the AMS 2 to the main nozzle and the HT to the aux nozzle. If you print with support filament often, it could stay in the HT, but you will need some way to keep the interior dry after drying filament.
When you want to dry other filament, you have to pack away the support filament in the meantime and reinstall it when drying is finished. You can’t print with support filament during that time, or you need the FTS so that you can also put the support filament in the AMS2.
But I doubt that you will find yourself too often in that situation.
OK. This is very useful information. The bundle and an HT and possibly the track switch sounds like the best choice. Appreciate all the responses. And it does look like you only need the filament track switch if you want either of two AMS or two HT to feed either of the two nozzles.
Lets say, for simplicity sake, you have 2 AMS-HT. Both connected to the track switch.
You are going to use both for a dual colour print.
How does this work with the track switch? Can it pass two colours and keep both colours loaded in the nozzles for the print, or does it keep retracting each colour since the track switch can only pass one filament at any one time?
If the AMS-HT are connected to 2 different inputs of the track switch the filaments will stay loaded (2 different inputs, 2 different outputs) but in this case unless you have/need more AMS connected why use the switch?
I have 4 AMS 2 Pro’s connected to my H2C. I wanted to connect the TS more for convenience - I’m just trying to understand the best way of connecting them ie, 2 on each TS port, or 3 on one port and 1 on the second etc, as for a 2 colour print, for example, I want to have both nozzles loaded simultaneously rather then having to pull filament back each time…..or am I overthinking things here?! lol