Downside to R2R Ladder DACs?

At therisk of being contentious: Aggressive treble is more a sign of poor clocking than a design fault of delta sigma dacs compared to r2r dacs. Even highend dacs benefit from reclocking with Mutec, Cybershaft, Antelope, sotm et al. There is no superiority in r2r dacs, they tend to be more euphonic but sometimes less resolving. YMMV

@cheeg the section labeled "Oven Control" in the Lavry DA924 user manual may be informative. The DA924 (DA2002 for consumers) was often considered a "gold" standard in professional audio DACs and not just for its color.

The specific sentence relevant to your question is:

The PCM DAC is constructed of custom made laser trimmed thin film resistor networks; yet any resistor is subject to short term drift due to temperature variations and long term drift due to component aging.

bs meter from that salesman just hit 100

suggest u trust him less going forward

Just to chime in on salesmen BS... I recently had this salesman suggest I’d buy his Audiolabs MDac because the other DAC I wanted to try out somewhere else was sounding worthless. The DAC I was talking about was the RME-ADI 2 DAC...