No concern, it's just another way to skin a cat. Sonically an all jfet low noise high input impedance mic preamp design does sound different. As I mentioned before, the higher input impedance allows the designer to use smaller value, higher quality film caps to block 48 volts in place of common larger valued electrolytic capacitors. It does allow one to inject high impedance sources without a DI box, but that's not even needed. Besides an all jfet design, I also have some with all transimpedance amplifiers, those are very fast and once again, different sounding. They run at over 100 mhz and sound very good.
Which ever topology I use, they all sound a lot better to me than the commercial stuff you can buy.