Imagine not knowing the definition of {banzu}, and being told that there is a gismu that means "enough/sufficient", what place structure would you intuitively expect it to have? Turns out not everyone has the same intuition here!

Personally I always thought {banzu} was a wee bit clumsy. The x1 can be anything, but it feels like sumti-raising most of the time. I tend to use a {ni} in banzu1:

    (1) lo ni mi certu cu banzu lo nu mi snada
        "The amount of [I am skilled] is enough for [I succeed] to happen"
        "I am skilled enough to succeed."

But there is also usage like:

    (2) lo xance cu banzu lo nu bevri
        "A hand is enough to carry it."

It's basically sumti-raising, since "having a hand" or "using a hand" is what is actually meant.

For a long time now, I have felt that {banzu} should parallel {sarcu}. {sarcu} is the "necessary condition", and with {banzu} there could be the "sufficient condition", which is a useful and necessary (no pun intended) word to have. The place structure would simply be:

    (a) x1 (nu) is a sufficient condition/is enough for x2 (nu) to happen under conditions x3

Everybody knows I like parallelism in Lojban, so such a definition would sit well with me. It's a pretty counterpart to {sarcu}.

    (3) lo nu mi sanga cu banzu lo nu mi gleki
        "Me singing is enough for me to be happy."    (also yet another case where nu/ka polymorphism would be useful)
   
This also adds an additional nuance to the Lojban conditionals:

    (4) banzu lo nu mi do fraxu kei fa lo nu do nupre lo ka na za'u re'u tai tarti
        "I will forgive you if only you promise me not to behave like that again."

On the other hand, latro'a, another Lojbanist, happened to not pay very close attention to the actual definition of {banzu}, and intuitively kept using a definition that they felt was appropriate. That definition was along the lines of:

    (b) x1 (object) is sufficiently/enough of x2 (ka/ni) for x3 to happen

In my opinion, this is also a useful definition! This definition is especially useful for lujvo, something which the actual {banzu} is terrible at, which I had to realize time and again upon trying to use it in lujvo. The natural tendency for me was to place {banzu} as the veljvo tertau, but then, where does the seltau go? The x1 is where it should go, but that isn't how lujvo tend to be formed. "Good enough" could be anything of {xagbanzu}, {bazyxau} or {selbazyxau}. In any case, it feels clumsy. This last definition makes making lujvo very easy, "good enough" is simply {banzu lo ka xamgu} -> {xagybanzu} (meanwhile I shed a tear over the fact that {banzu} has no short terminal rafsi).

The big point here is that I believe that both definitions, definition (a) and (b), are useful and should have a brivla. They can't both be {banzu}, however. Either we give one of them {banzu} and make a lujvo for the other, or we create a new gismu for one of them. I don't really have a preference for one option over the other, I just hope that both meanings end up with a nice brivla. Or rather: both definitions getting a brivla is a sufficient condition for my happiness! ;)

It sucks that you only get fai when using jai. There are many cases where it would be cool to get a fai'd non-x1 place. The fix {SEjaiSE} is ugly and wordy and Lojban deserves better.
Let's say we want to say "I allow you to kiss me".
There are two ways that require nothing new to be invented:
(1) mi curmi lo nu do mi cinba
     "I allow that you kiss me."

(2a) mi se jai se curmi do fai lo nu cinba mi
(2b) do jai se curmi mi fai lo nu cinba mi

Sentence (1) is of course fine, but suffers from one small drawback: It requires forethought. If you already said {mi curmi tu'a do}, you are screwed and will be the laughing stock of your friends (zo'o).
Sentences (2a) and (2b) are similar, but (2a) is much uglier. (2b) I would consider quite normal and beautiful, but here we had to rearrange the sumti to make it work, again requiring a certain amount of forethought.

What I propose:
Allow fai to refer to tu'a places when no jai is present:
(3) mi curmi tu'a do fai lo nu cinba mi
     "I allow you to kiss me."

If people complain about this, then at least invent a FA that does this job. It could then be used even when a jai is also present. I propose fau'a in that case. However, I don't like inventing new cmavo all the time. In my opinion, it's better to extend the use of existing cmavo.

I propose to allow any VUhU to appear anywhere a JOI can.
This makes sense because VUhU are (usually binary) operators just like JOI and using them in other places than mekso makes sense.

Advantages:
# More flexibility
# Allowing mekso to be used in more places = more utility of a huge part of cmavo space

Disadvantes:
# Pretty much none. It makes things grammatical that weren't before, but it does not break any usage.

Definitions must be found for all the use cases, e.g.:
SUMTI VUhU SUMTI, SELBRI VUhU SELBRI etc

If VUhU *moves* to JOI, JOI has to get all the mekso definitions as well to make things like (1) grammatical:
(1) li pe'o joi paboi paboi du li re

So it might be easier to just give VUhU more rights and allowing it in places that JOI can go, but not vice versa.

Examples

(2) lo mu bakni su'i lo mu kanba cu zilkancu li pano lo danlu
"5 cows + 5 goats amount to 10 in animals"

(3) lo mi lanzu vu'u ba bo lo mensi noi cliva bilga cu zvati lo nunsla
"My family minus-later my sister, who had to leave, were at the party."

This removes some of the awkwardness of mekso and makes it more intuitive and less verbose. I opine that the above example sentences show a useful application of what this proposal entails.

This proposal is not very detailed yet, but I can flesh it out, should there be desire for constructive discussion.