That's a good question and one I'm not likely to find out
But I would think they would be A LOT flatter. If you're getting 3200 fps with your 210's, I would guess you could probably get 3550-3600 with the 168's.
Just for grins, I tried some RL17 (86 gr) with 180 E-Tips out of my 26" 300 RUM and I got about 3400 with that combo, which basically equalled H1000 and Retumbo. They shot well but I didn't like the low case volume so I went with Retumbo. I would think with the lower weight bullets, RL17 might outrun H1000 and Retumbo in the 300 RUM and you could probably get a few more grains in the case.
If you really wanted flat, the GS HV 177's would equal or exceed the 168 velocities with A LOT higher BC, .6+. One of these days I want to try the RL17/GS 177 combo. Should be interesting. It would way out run any of the big 338's except maybe the AM.
Just some things to think about...