I also need the roles system. Also I studied it Scott Guthrie's work.
Although it is very nice explained, I think I would give it a thumbs down.
I'd prefer it if the profile table was generic and with fixed columns, and
the profile properties were records in that table. Dealing with the property
types, can be handled by examining the value_type field. I have done this
project in the past, and it works like a charm and that's what I want to do
now.
(starting a parenthesis here)  

Table OPTIONS(userId, name, option_group_name, label, value, value_type,
value_mask, SQL_needed, lower_limit, upper_limit, date_changed, comments,
sort_order)

That way, no changes are made to the table and stored procedures, when a new
option is added or deleted. I'd like a comment on that, by Scott Guthrie if
he sees this post. By the way, I very much like the way he explains his work,
as I study it now and then. We need guys like him. (end of parenthesis).

Going back to the membership issue, what I need is:
If I inherit from the SqlMembershipProvider in order to just override some
methods to add more info to my users, will the membership system be able to
call my new overriden methods? I wouldn't like to rewrite the whole
MemberShip provider from scratch by inheriting from MemberShipProvider class.

TIA