Almost without exception, pre-sprays perform best if they are applied, agitated and then left to dwell as appropriate.
You can do this with both the machines mentioned, but many CCers I've come across tend to use a powerbrush/wand as part of the extraction process, so unless you have really high spec extraction equipment, it is more difficult to maximise the performance of your entire system and chemicals.
A significant advantage of a seperate machine from the extraction kit, as with the Sebo, Envirodri etc. etc. is that an assistant can agitate for you in advance whilst you are using your extraction kit in another area. Can save quite a bit of time.
I am aware that you could use a powerbrush independently for agitation immediately after pre-spraying.
The Sebo Duo is an extremely low cost piece of kit, so my head would say buy this first.
Safe and happy cleaning

The Ken