Blind steal - value bet or free showdown?

[toby]

Villain seems normal/decent. 18/5 after 60 hands.

Party Poker 2/4 Hold'em (9 handed) FTR converter on zerodivide.cx

Preflop: Hero is Button with 5[img]/images/graemlins/spade.gif[/img], 9[img]/images/graemlins/heart.gif[/img]. CO posts a blind of $2.
<font color="#666666">5 folds</font>, CO (poster) checks, <font color="#CC3333">Hero raises</font>, SB calls, <font color="#666666">1 fold</font>, CO folds.

Flop: (6 SB) K[img]/images/graemlins/club.gif[/img], K[img]/images/graemlins/diamond.gif[/img], 9[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(2 players)</font>
SB checks, <font color="#CC3333">Hero bets</font>, SB calls.

Turn: (4 BB) 2[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(2 players)</font>
SB checks, <font color="#CC3333">Hero bets</font>, SB calls.

River: (6 BB) 4[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(2 players)</font>
SB checks, Hero ...


Is this a clear value bet, check behind, or close call either way?

A better hand clearly won't fold, but that would have to be a slow-played K or flush draw that just came in, or a better 9 (which is basically all other 9's).

Worse hands that might call are lower pp's or an Ace.