I have time with formuler f2 turbo and I must to say it is very good reciver. Cost me 70 pounds, i used openatv 6.1 was very stable didin't any problem at all.
i have been using the formuler s turbo box for a while kodi iptv and just got myself the f4 turbo which i use with vm and motorised sat dish easy to set up
its a great box, very fast, good clear picture...its a small silent box and for the price its a bargain
USB recording works great no delay
the only negative would be the remote control, its not well balanced (ok button and main controls are too far down) however there is a plugin you can use, i have my xtrend remote working mine
I love the fact you can combine sat, terrestrial & IPTV into one box and record to usb or NAS and link to other Enigma2 boxes on the network. Great box at a great price.
Forgot to mention one of the other things I love about this box is the Picture-in-Picture ability which means I can keep an eye on a second channel while watching main, something I've missed for years.
[Edit: I would have edited above post but now see the edit button is only displayed for a short time. I'm new here ]