Questions regarding vac-based

Hey guys,

I’m new here. English is not my mother-tongue language, so sorry in advance for any misspellings and errors, I’ll try my best to avoid from them.

In short:
I got sizegenetics device a month ago. I had problems with the comfort of the noosing strap, and all in all I’m thinking of purchasing a vac-based extender.

I have some questions, in order to decide what to do.
If you have any relevant experience then it would be really great if you can share your knowledge.

1. Is there a difference between a vac-based extender and a strap-based? I mean in terms of comfort and potential injuries.
2. Do you recommend on a particular one? I read here some posts about PeniMaster; Phallosan Forte; and VacExtender.
3. If I’ll eventually buy one, do you also recommend buying a belt or other accessory?
4. Can you wear the Vac-based device under the pants (large pants)? And while sitting down?

In my view, the most important thing Is the potential to get injure, the comfort, and the simplicity of usage.
I honestly don’t care that much if it works fast or slow, the main thing is safety, and in my understanding - safety factored from comfort, simplicity and low potential to get injured.

Thanks!