As it was stated, it does really take away from any technique and keep the lift in a straight plane. So depending how much "technique" you use with freeweight, the difference can be larger. I havent done smith in a while so its hard for me to compare.
On the machine I used I dont remember the difference in reps being too large between smith and freeweight. I havent tested this in a while though. Sometimes it feels more difficult. If you can get 315 on smith you are probabally not too far from getting it on freeweight. Might take some weeks to get used to stabilizing the weight. I once used smith for behind the neck and in front, military presses. I havent done it in a while though, since I do mostly side lateral work for delts now, and since I do alot of chest work. "Respectable" is all a matter of perspective. At the gym I train at though, youd definately get some looks for putting up that kind of weight on incline, smith or freeweight. Sounds like your getting strong to me. KEEP KILLING THAT SHIT!!