members vs. guests

As I'm quite interested in who clicks what, meaning registered users vs. guest, would it be both allowed and wise to use a code like this to place my ads?

<if condition="$show['member']">
google code1
<else />
google code2
</if>

Sure, there's nothing wrong with that.

98% of my clicks are from guests.

If your adsense is linked to your analytics account then you can check that in analytics.

Visitors > User Defined > Adsense Revenue tab.