zipcpi: The case against "lo"
Note: the title is an exaggeration. I still use lo the most often out of all the gadri; this is merely an argument as to why alternatives are needed.
Here is the problem: lo (post-xorlo) has [at least] four meanings.
Specific/deictic case: There are specific referents within the universe of discourse that I wish to refer to right now. E.g. "Give me the two apples." (probably the ones you're holding, or on the table nearby, or that we were already discussing.)
Non-specific case: There is a set of referents that I refer to, but the difference between the members within the set is not important. "Give me any two apples."
Generalistic case: I am generalizing about a set of referents, without making any comment as to which members they apply to. "I like apples." "Apples are delicious."
Definitional/essentialistic case: I am defining or expressing an opinion about what distinguishes a member of the set of referents, from a non-member. "Apples are a type of fruit."
(Note that ro broda cu brode is not an adequate answer for this case, as the fact that ro broda cu brode may be coincidental and not definitional to broda. E.g. xu ro remna cu mroka'e = "Are all humans mortal?" -> "go'i/Yes", but whether "humans" are defined as "mortal" would be a very different question.)
Most of the time, this ambiguity is not a problem (context is a pretty powerful creature), but it often is beneficial to disambiguate. [e.g. Did you like the play? (probably the one you just watched), or Do you like plays? (in general)]
Unfortunately, as defined, Lojban currently lacks a system to easily disambiguate between these cases. There are some people who use le (and less that use lo'e) in an attempt to disambiguate, however, their definition is unclear (le in particular was initially defined using the "veridical/non-veridical" distinction, which lost popular favor and led to xorlo), hence causing other Lojbanists to avoid them altogether.
The gadganzu proposal (as well as the experimental UI xe'e for the non-specific case) is one proposed solution, but, if you think you can come up with a better one, feel free to discuss it. I just want there to be a solution.