Well, first off, most applications cannot use mixed sample rates within the same project. So, if you other audio is at say 48KHz, you would not be able to record vocals at 96 anyway.
Second, I don't think in the end that you are going to hear a significant difference between 48KHz and 96KHz sampling rate. Yes, there would be a slight difference, and certainly if you could do your whole project at 96KHz that would probably make a nice little difference in the overall quality. But, I have used 48KHz sampling rate for some time now and seem to get very acceptable results.
The Lynx One card has very good A/D/A converters on it. Better than most soundcards on the market has in my opinion. It isn't JUST the converter chip that is the difference. Lynx developers did a very good job in the analog end of things too. I think you will be able to achieve very good results with that card, even with it's "limited" 48KHz max sampling rate.
Good luck.
Ed