optifine seems to be hit and miss with tekkit/technic packs. I've used various versions and found the basic to have the fewest problems. My latest attempt resulted in a problem with blocks updating, for example torches wouldn't fall if the block they were attached to was removed and fluid blocks wouldn't show that they were flowing which led to a few lava deaths before I just ditched OF.
Fortunately Sphax works rather well without an HD add on I just don't get lava/water textures and the font isnt high res. If anyone know of a program that can fix those two things I would be much appreciated as OF is not worth the hassles it causes and MCpatcherHD doesn't want to get its act together for some reason.