It does result in some strange synergy. Duskblades have a number of rays on their spell list, so the switchover to archery would make those spells more or less irrelevant. They're generally ignored anyhow, but they'd be even MORE useless for a class that already is limited in its choices.

I guess the only risk is that you suddenly have spells that are touch range only reaching as far as you can fire your bow. Imagine suddenly being able to paralyze someone from 100 ft. away. At 3rd level, 3d6 electric damage from that distance is going to be hard to deal with.