tl;dr:
For DC-powered devices, the MyVolts solution recommends daisy chaining devices, you can do that way cheaper, and in a more flexible way that does not limit the layout of your setup in the same way the MyVolts solution would. But you can mix and match with MyVolts stuff to achieve the best of both worlds
The long version:
Since they now fixed all Elektron devices (oxcept for the Overhub MK2) in the PowerMyGear App, and I experimented with it a bit more, because the app tells you exactly which parts you need to set everything up when you hover over connections.
It’s probably obvious to you, but then it might be worthwhile for other people to read that. Here’s the setup I used, so you can see for yourself:
- devices with the same voltage and polarity are simply daisy-chained to one output until that output’s power is exhausted.
- sometimes they use converters after their daisy-chain cable if the barrel plug is a different size
- sometimes they use polarity inverters
- each device that is USB-powered gets an individual port
This can, of course, can be achieved entirely without their expensive hardware, even for portable setups if USB-noise is not an issue.
For all your DC-powered devices, the simplest and most cost-effective thing that can be done to reduce clutter is getting a few strong and reliable PSUs (prices vary, branded 12V PSUs with 80W cost around $35, see this thread) and then daisy-chain your stuff.
The daisy chain cables recommended by MyVolts are not a good idea, because they are expensive ($10) and too short (30cm), and thus would define the layout of your setup, which is a bad idea. One way around this is to get a decent but shorty daisy chain cable with a suitable number of outputs, and then use DC extension cable of with the appropriate lengths. If bought some on ebay last year that are 60,90 and 150cm, for ~$5 each. You can secure the connection with heat shrink tubes, and I recommend putting labels on the end of the cables (device, or voltage and polarity). Secure unused ends of the daisy chains with some tape, or also put a heat shrink tube on.
You can get PSUs with different polarities if necessary, or use polarity inverter cables.
If you want to know how much power your device requires: check the PowerMyGear App 
One nice thing about the MyVolts solution, but also about what I describe here is this: if you buy and sell stuff, this would not affect your powering solution much, as long as you have a few extension cables at hand. Only if you require a new type of connector, or the maximum power your PSUs provide is exhausted you need to figure out how to extend your powering system. Until then, you can simply use the PSU that came with the device.
Unless you have noise issues with your USB-powered devices, get a powered hub (one with individual switches if you prefer switching devices on and off individually), with an appropriate number of ports and a PSU that is strong enough, e.g. this one I have for $90 that has 16 ports and comes with a 60W PSU. With that you can connect all your stuff to your laptop, too, in case you need to.
I think there are cases where the MyVolts solution would make things simpler, because you don’t need a dedicated PSU for each voltage, but you can mix and match a setup that handles the most common things (9V/12V) via separate PSUs, maybe add a Ripcord or two to a powered USB-hub for the occasional device that would require 3V or 5V, and only user an Alchemist actually makes a difference.
And since you need to do some planning anyway, because what the App recommends is in no way the only, or even the best solution for your setup - you might want devices in different places, and find other combinations of converters and inverters etc. - you might just as well create your own solution and save some cash.