I have the FTDX10 working fine with varac / vara hf. if you have whatsapp / telegram / messenger / skype I could help you out.

Discussing technical matters is easy. You can measure, evaluate them. Add the human factor and logic get flushed down the toilet. For conversational contacts, Olivia is very solid and one of the best options. Yet very few use it. VarAc, is based upon VARA and adds the integrity, paying a toll in speed with very low signals. It allows to send files, where the integrity importance is obvious. Popularity of FT8 exploded in the last few years, with very many operators operating fully automated stations and just checking the log once they get home after work.... I personally couldn't be any less interested in FT8; but many others are, and that's perfect to me. I see more of a problem in terms of VarAc popularity with people constantly remaining on the calling frequency and blocking other traffic.

You are comparing apple to oranges. If you want to transport your morning bread, you won't use a 40 T truck. If you want to transport 40 T of goods you won't use a sport car.... Vara, like Pactor, is an ARQ mode. The very idea of an ARQ mode is to preserve the integrity of the data. That's why such modes are used in networks like winlink. ARQ mode will adapt speed when needed in order to get correct packets. Thus, they are slower than FEC mode, where data integrity is not provided. For pure conversational contacts other modes, like Olivia, are faster.

the VARA protocol is ARQ, so if you are not interested in data integrity you'd better use any of the FEC modes. The ARQ takes places in the transport / datalink layers, so it's part of the protocol, you can't just turn it off.... It would be interesting to have the capability to read the packets at these layers in the monitor window, and see what's going on in the communication between the modems. It is somehow possible, as many years ago we were doing just that for work on other ARQ protocols, but I guess it would require more work and maybe only few would be interested.