Hi,
again thanks to all. Rally useful links Mr Rork
I come from modo (before modo, Blender and Silo). I can say Modo is a nice app (after a bit customization, out of the box is not so nice)but he has more bugs then tools... Modo crash too frequently for my taste and, finally, cannot get in agreement with Shader Tree.
In any case, look more oriented to architectural visualization (real measure, bevel with many archiviz profile, item layout and great render preview) and, in comparative with SI is rally inexpensive (offer rally lesser, but if you don't need ICE, animation ecc. I think it is right choice: 800 $ and no annual subscription), and don't forgot Modo sculpt is nice too. In any case, Luxology development is slow.
for my need, XSI look (at the moment) a super cool modelling package (sometime I find strange bugs... I will open a thread about)
Well, XSI is gr8 choice than. I read subject line and made conclusion that u need it for exclusively for Archviz.
No, sorry If was a bit vague, I answer only because sometime, someone, ask me about this

so, only my interest. Tanks for you sentence
About Modo, Luxology just know how to do things. I think that in this release is every single thing that users mention on their forums from version 401. Except CA tools.
It is good to own that app.
Agree, in any case, I think, if you need archiviz, Modo can be a nice companion to XSI