trying to sell estate land...

QFT. BUT.

Even the most unscupulous estate owner can be personable and charming and therefore have a better rep than they deserve ...

How? The story shown that "s*it happens". I wouldn't go OT mention again the gink0 thing... but well, until the bad days it was considered an "institution", kinda like something "official", something to trust without doubts... and thousand of ppl lost everything.
So there's already a regulated market about land selling, and it's on mainland: the rules are precise, you cannot go wrong by a mistake, and you don't have to "trust" anyone else than the company offering you the whole service (Linden Labs); while on estates you are forced to trust someone that is not involved in any way in the service management.
So what i have to research? Do I have to ask FED about the financial of the sim owner? I can evaluate Linden Lab Company and decide if Second Life is stable or it's gonna die (so i decide to invest money here....), i cannot do the same with an unknown estate owner that may simple disappear from a day to another (the fact he plaied fair until today doesn't change anything... he may do it tomorrow for 100000 different reasons).
I'm giving you money, i would like to receive back a sort of guarantees not just your precious "word". I think this is the way to conduct a fair and honest business.

IF it were to happen, I don't think classifying estate land purchases as rentals with entry fees would hurt estate land sales much in the long run. Experienced residents know that is what they are buying and will continue to purchase the land as they did before. Inexperienced residents will realize that they have to research the estate owners which shouldn't bother any reputable estate owner, and will also allow such buyers to make better informed decisions in general about the risks of their investment. Estate owners would essentially be losing a marketing tool. I don't think it's really necessary to make such a change though. We see the occasional post here and there of the sell and evict scam but as long as these remain in the extreme minority I don't see any reason why estate owners should lose this marketing tool which most probably value to a great degree.