Is there any reason not to do this for a startup that qualifies? Specifically are there any drawbacks if the gain exceeds the $10M maximum? I noticed that it u

Is there any reason not to do this for a startup that qualifies? Specifically are there any drawbacks if the gain exceeds the $10M maximum? I noticed that it uses the old 28% capital gains rate, which is higher than what it is now (15-20%). Does that mean if your startup "goes unicorn" you get a tax break on the first $10M but you end up paying an extra 8% or more on the rest? And therefore this is only a good structure for startups aiming for smaller exits (hence the "small business" stock)?