darkweasel:We aren't talking about "legintos" but about "estintus".

There is a reason to group them together (below).

darkweasel:In practice I see -intus forms commonly used, and they are not too hard to understand..

It seems to me that estintus and devintus have become like neologismoj, as approximate translations of 'would have been' and 'should have', and the users think no further about the complex tenses involved. Thus if the neologismoj estozozis and devozozis had been invented in their place, the effect would be the same.

My point is that if words with complex tenses are memorised and used as shorthand approximations in this way, and the complexity of the tenses forgotten for practical purposes, then Esperanto becomes in that sense just another natural language. Better to prefer solutions that preserve the simplicity of the language and its mode of expression, which is a valuable part of the Esperanto tradition.

darkweasel:Even English uses something like -intus. estintus = would have been

True, but think about how similar "would have been" and "estintus" are:
would = literally the past tense of "will" (estontis)
have been = have + be's past participle =~ "intis"

Which effectively translates as "estontintis" (or even more shockingly "estontis havintinti", depending on how literally you want to translate things). Now quite frankly that logic ain't gonna make sense to no one!

(furthermore, many English speakers don't even recognise what "would" or "have been" actually mean, they just put the words there because that's how it's done. To be honest, English verbs don't even have a conditional tense, it's just modal verbs in the past tense)

I am so glad to have a forum to come to where people who know more than I do can help me out. Thank you to all of you who gave your input. Tommjames and Miland, thank you for your quotes from the PMEG. The discussion that ensued was excellent, and as an Esperantist, it gratifies me to see how seriously we all take the style and use issues of our language. I've learned a lot from this discussion!