Firstly my Grail is the SB, not SE, sorry. I have had it about two years.
The model range is Grail, entry. SB, separate power supply on umbilical, but same amplification circuitry. SE, separate supply for each channel. SE+, some selected components. SB and SE can be run balanced or single-ended but input and output must be the same mode. One might have presumed the SE is single-ended and SB balanced. Not so.
The reading of the literature you mention is a mis-reading. In the vdH specs it is stated that the current operation provides automatic matching for cartridges in the 40-400 ohms. On the SE and SB there is the additional possibility of changing the capacitance by hard-wiring capacitors into the back of an XLR socket. vdH suggests this might be done in the case of moving magnet cartridges but doesn't see the need on moving coils.
I have listened to a wide range of top-end MC cartridges on the SB and it works well with all of them. It is priced at c.£14k in the UK, but I believe cheaper in the US. In my estimation it is at least a match for amps selling at double that. For instance I tried the Boulder and found that to be dry and over-clinical, analytic rather than musical compared with the SB. I found it noticeably better than the AR Ref 3 and lesser ARs.