I am considering purchasing a Helikon cartridge...

I am using the Helikon with ARC PH2 and LS25.
With a little patience, it will reward you with superb performance, but as Futterman indicated, you need to give it at least 100-200 hours.

For a richer tonal balance (without losing air and definition) try loading at 100 ohms.

The recommended loading of 100 ohms was specifically for the ARC PH2/PH3/SE and LS25 combo. As you indicated, results will vary depending on the system, personal preference, etc.

The Jadis/Aesthetics combo has a warmer tonal balance (IMO) than an ARC PH2/3 and LS25 front end. The ARC combo tends to be more neutral (leaner to some) sounding in the midrange. This difference in tonal balance, presumably, leads to the different loading preferences.