In case you don't know, "Flexi" is a popular short way of saying "Flexible" and fits perfectly with "Bet" both in meaning and in aesthetic pleasure.
Just a quick interjection from me, unfortunately I haven't followed the whole discussion here enough to provide more input.
In German, "flexible" is abbreviated to "flex" and I seem to remember that this is also the case in English. As a result, "flexbet" would actually be a simpler and easier to read alternative to "flexibet", where I would agree with the previous poster that the "i" interferes with the reading and memory flow.
You'll be forgiven on the basis that English language is not your native language.
Flex is an independent English word which means among other things: to put a (skill, talent, or ability) to use.
"the talks were seen as a way for Merkel to flex her well-known diplomatic prowess". It is not the short form of flexible. I don't know about German as I neither speak nor understand the language.
Flexi on the other hand, is a system permitting flexibility of working. Therefore, "Flexi" as a prefix means Flexible.
Flexi is also a popular term among businesses. There are countless of companies (especially banks and telecoms) naming Flexi to their different products.
Thanks