Before:

def self.find_expiring_soon(date_time = Time.now)
@@expiring_soon ||= find(:all, :conditions => ["type_id = 1 AND completed = 0 AND created_at < :date", { :date => (4.months + 14.days).ago(date_time) }])
end

def self.find_expiring_soon_with_donations(date_time = Time.now)
@@expiring_soon_with_donations ||= find(:all, :conditions => ["type_id = 1 AND completed = 0 AND donated_amount > 0 AND created_at < :date", { :date => (4.months + 14.days).ago(date_time) }])
end

def self.find_expiring_soon_without_donations(date_time = Time.now)
@@expiring_soon_with_donations ||= find(:all, :conditions => ["type_id = 1 AND completed = 0 AND donated_amount = 0 AND created_at < :date", { :date => (4.months + 14.days).ago(date_time) }])
end

def self.find_expiring_very_soon(date_time = Time.now)
@@expiring_very_soon ||= find(:all, :conditions => ["type_id = 1 AND completed = 0 AND created_at < :date", { :date => (6.months - 3.days).ago(date_time) }])
end

After:

def self.find_expiring_soon_with_donations
  find(:all,
       :include => :donations,
       :conditions => [
         "expires_soon = 0
         #{with_expiring_criterias}
         AND donated_amount > 0", { :date => four_months_and_a_half_ago }])
end

def self.find_expiring_soon_without_donations
  find(:all,
       :conditions => [
         "expires_soon = 0
          #{with_expiring_criterias}
          AND donated_amount = 0", { :date => four_months_and_a_half_ago }])
end

def self.find_expiring_very_soon
  find(:all,
       :conditions => [
         "expires_very_soon = 0
          #{with_expiring_criterias}
          ", { :date => (6.months - 3.days).ago(date_time) }])
end

def self.find_expiring_now
  find(:all,
       :conditions => [
         "expired = 0
          #{with_expiring_criterias}", { :date => 6.months.ago }])
end

def self.with_expiring_criterias # DRY
  "AND type_id = #{ElementType::MONEY}
   AND completed = 0
   AND activated_at < :date"    end    

private_class_method :with_expiring_criterias   

def self.four_months_and_a_half_ago        
  @@FOUR_MONTHS_AND_A_HALF_AGO ||= (6.months - 6.weeks).ago(Time.now)  
end    

private_class_method :four_months_and_a_half_ago

• Much more lines of code (LOC), does it improve readability and understading?
• hardcoded values replaced by objects (ElementType::MONEY), does it make easier to understand the meaning of numbers without knowing the DB model
• duplicate SQL DRyed in a private method

Which version do you prefer?