NLHE Preflop - With which hand to raise more often? 88 or 89s?

[kbinder]

Suppose you're in a live 1/2 or 2/5 game where there is a lot of limping preflop. 3 people limp in front of you, and you're in late position. With which hand are you raising more often: 8[img]/images/graemlins/spade.gif[/img]9[img]/images/graemlins/spade.gif[/img], or 8[img]/images/graemlins/diamond.gif[/img]8[img]/images/graemlins/heart.gif[/img]?

Calling here is obviously ok if we know we can count on our opponents to build a pot if we hit big with either hand. If we cannot count on this to happen, we may consider raising so as to build a big pot for when we hit our hand.

As far as comparing the two hands goes, the main question I want to consider is how often I will want to play a big pot once the flop comes. Excluding flops like 6[img]/images/graemlins/diamond.gif[/img]7[img]/images/graemlins/diamond.gif[/img]9[img]/images/graemlins/diamond.gif[/img], the only time I'll be willing to play a big pot with 88 is if I flop a set, 11.8% of the time. When I play 8[img]/images/graemlins/spade.gif[/img]9[img]/images/graemlins/spade.gif[/img], I'll want to play a big pot if I flop a combo draw, something like 6[img]/images/graemlins/spade.gif[/img]7[img]/images/graemlins/heart.gif[/img]Q[img]/images/graemlins/spade.gif[/img].

Intuition tells me that I will flop a set with 88 more often than I will flop a combo draw with 89s. (This may not be correct). Push aside any business of mixing up your play, and this seems to indicate that I would want to raise more often preflop with 88 than with 89s.

Are there any reasons why it would be better to raise 89s more often preflop?