Regarding modern standard class gliders such as LS8 in Club Class, my opinion is that given an appropriate handicap factor, they may be perfectly acceptable provided ballasting is prohibited (as it is in the FAI definition of the class).
FAI leaves a lot of freedom about national rules for the gliders eligible in club class events (excluding those sanctioned by FAI at world or continental level).
In Italy we strictly apply the "IGC club class handicap list" which includes small adjustments for wingloading (think: Discus bT, PIK20E). The actual handicap for a single sailplane after the adjustments shall not exceed the max. accepted hcap factor indicated in the class definition.

Aldo Cernezzi