[exim] Suggestions on which Spamassassin?

Hello

This is what I am planning to do.

I will set up 2 or 1 frontend server(s) with Exim and Spamassassin(lower mX) which will relay to my 2 mail servers with higher mx records by means of smart host.

1-I will not give my users the ability to make custom rulesets. There will be only one ruleseset for everyone.
2-Perormance is a very important issues for me(I have seen spamd is said to be suitable instead of regular perl sa.) and I have a looot of users.
3-I will not do any virus cheking on this frontend because I already have Kaspersky License which I know doesn't go well together with Exim...
But Thats not too relevant.

My First Question:
I am going through the options and reading Tim Jackson's nice walkthrouh. It seems that Sa-Exim looks best fit for my needs? Or is it not?

Second Question:I am not an advanced Exim user with limited Exim mechanism knowledge. Is it possible to Set Up 2 Front End Exim's with DNS round robin and according to the recipient address the frontends will hopefully scan and route the mail to one of the correct backend mail servers?

Any suggestions or flaws on this besides the usual local delivery problem?
If there are any of you outhere which use a similar topology I would appreciate it if you help me out by eather sending to link to a previous post or document. At the moment I am still googleing..:)


Thanx.
Serhan