Paul
I have used and tried several for my own use. Overall I found them to be more time consuming than useful.
The problem was not in deriving a format for relatively simple properties where the data was straight forward. The problem was in inputting the necessary data for all the sales which we recieve. Since one tends to use the sales with the best data, I found that I tended use use some sales a lot, and others I never used even though I spent a lot of time developing the data and entering it into the model. So, you have a data base you spend a lot of time inputting data to keep current but gain relatively little in return for your work effort.
The reason is that it was my experience that what is important in one sale is not important in another, depending on the subject. You need to be able to screen all the sales for the requisite data, but may not have it for all sales. The ratio of these items also matters. As an example, the amount of flood plain may be important in one sale, the floodway in another, the P/S/F may be relevant for the typical warehouse, but the cubic volume or the ceiling height may be the important factor. Writing the model to be able to account for all of these items in a meaningful way was not impossible but difficult, and obtaining the data for all the various fields for all sales was a herculean task. Also, much of the data is time sensitive. If you have a large shop, and you have a trainee wantabe, and you can afford to pay this person a salary, it would be ok, otherwise I found it to be too time consuming.
Regards
Tom Hildebrandt GAA