Downside to R2R Ladder DACs?

Not true at. All , a quality resistor such as what you see in amplifiers, preamps last for decades, capacitors wear out before resistors , resistors control resistive values and dissipate very little 
heat especially in digital where it is low voltage .i have modded for over 20 years ,just think. How many years you may have Held
onto a a piece of electronics And it still works I have tunes 30 years old still working and quality resistors just  keep doing their job ,look at Vishsy naked resistors for example less then .5 watt
and rock solid used for years and tolerances on average well under 1%, if matched by the hundreds better still and won’t drift for many years wear a capacitor is constantly changing a resistor 
is a constant. I had a AbN 1704 R2R  dac for over 15 years sold it and still working .

Thank you all for your responses. ITT is reassuring to hear that many of you have had good results with your ladder DACs, but those who compare this situation with normal circuit aging issues are missing the point. The reason why resistor degradation could be much bigger issue in higher quality R2R DACs is that the algorithm used to design them demands extremely tight tolerances in resistance value to achieve a small improvement in sound. For example, the Denafrips Terminator specifies resistance values of 0.005%, and 0.02% is common in less expensive designs. In amps and preamps, a drift of 1% in resistance is usually not audible; in a ladder DAC, it would make a huge difference. As stated in @nekoaudio’s post, the Lavry DA924 user manual notes that even custom made laser trimmed thin film resistor networks are “subject to short term drift due to temperature variations and long term drift due to component aging.“ Clearly, the potential is there for R2R DACs to degrade faster than other designs; I’m curious whether any Agoners have experienced this firsthand?

Hi,
I have A/B tested 89 different DACs and your sales persons is just selling you. R2R DACs are my favorite and I have never heard any of them deteriorate with usage.

Cheers,

Sitting here listening to a pair of PCM-63K's in my 25 year old Dac and things sound better than ever. I concur with above sounds like salesperson agenda BS.

As several people responded here that they’ve had their R2R DACs for decades and still love them, I think you have your answer.