If fiber runs 1gig fine, are there any concerns when considering upgrading to 10gig transceivers?

Solution 1:

Presumably you're using MMF, not SMF. If you're running SMF, you'll probably be fine.

Check whether you're using 62.5µm or 50µm fibre. It's probable that your transceivers will only support the 50µm fibre. As well, you'll want to use OM3 or OM4-class fibre as OM1 or OM2 likely won't work well.

Solution 2:

Late answer for the OP but perhaps helpful to someone.

You can run 10Gbase-LRM over OM1-3 or FDDI fiber. With lower quality fibre you want to use mode conditioning patch cables.

http://en.wikipedia.org/wiki/10-gigabit_Ethernet#10GBASE-LRM

http://www.lanshack.com/ModeConditioning.aspx