Harald Schneider loupes

[diamanter]

Guys, sorry to bother with it... but could you please advise me a bit? I am considering purchase of a Harald Schneider loupe and there are currently 3 models in stock: 1) classic grey one, 18mm field, 2) GemologyPro L1, 20mm field and 3) the newest L2, 20mm field.
Could anyone compare them? Do you feel GemologyPro being better than the oldest model?

Thanks to everybody in advance!