if you're having it all taken apart, have him do everything. when i worked in the shop we would almost never replace one seal behind the timing belt. if the timing belt comes off, we told the customer that they should all be replaced. and this was not a sales ploy.
if just the crank seal is leaking now, the oil pump and o-ring will leak shortly. replace oil pump seals(o ring, and grey rtv cement between oil pump and block), front crank seal, and cam seals as well as timing belt. we saw far too many "well just do that one" sort of things. a month later they come back, yelling and screaming b/c they are leaking again, and we didn't fix the problem. it just saves time and energy, and money to do it all at once. and then you're good to go for another 60-100k.

-PJ

 

This is a VERY common leak for all Subaru engines, which is why they made the pumps resealable, all of the expert Suby mechs have told me. I have the same leak and they said the most important thing to do is CONSTANTLY check your oil level if you have ANY leak b/c the valves are very touchy about the correct level. On mine I actually heard a bit of tapping from the valves when driving it cold when my levels got a bit too low. Sure enough when I topped it off, the noise stopped, so that's what you need to "keep an eye on". Once you start smelling burning oil (leaking enough to drip onto pan, block and headers), you shouldn't wait more that a couple weeks or 7,500 miles at the most if you can b/c your timing belt will get oil soaked making it heavier and feels kinda laggish when cold- mine does cause I haven't been able to fix mine either....so, yes, do it ASAP.

-A.