One thing I did notice, if an asset does not already have a MACRS S/L depreciation method, the automatic switch to ADS will not work.  Some Tenant Improvements had been input as 15 year 150% DDB (§1245) property and  checking the "Apply switch to ADS for prior year asset" box on depreciation input screen 14 had no effect.  I had to select depreciation method 67, "MACRS 15-year SL Improvements," and then it worked.

Otherwise, I did not have any trouble with it.  I only checked the "Apply switch to ADS for prior year asset" box and made no other changes.  Lacerte automatically switched to the ADS life and correctly calculated the remaining SL depreciation.  I prepared an Excel spreadsheet with my own calculations for SL recovery of the adjusted tax basis over the remaining ADS life and Lacerte is within $2 on all but one asset, and that one is still within a fraction of 1 percent on a 3.2 million dollar asset.