"Is the 41(g) carryforward limited to the 2015 pre-PATH law in 2016, or that c/f now unrestricted and s/t TMT:tax limit? "

Ah, I see your problem now.  For that, I would refer to §38(c)(4)(B)(ii) which stipulates that the credit determined under section 41 ***for the taxable year*** must be with respect to an eligible small business.  Furthermore, legislative history is clear clear that this provision is for "research credit determined under section 41 ***for taxable years beginning after December 31, 2015***."

Since credits for each taxable year are first determined under the respective code sections (in this case §41(g)) and then subject to the relevant limitations (in this case §38(c)), I would surmise that carryover from tax year 2015 would not be eligible for §38(c)(4) on the basis the credit was for a taxable year prior to January 1, 2016 (even if it were a ESM in that year).

This essentially means that credits from these carryover from 2015 would be limited to the TMT.  To achieve this, you will need to enter the carryover credits on Screen 34 by clicking on the "Elections/Carryovers/Overrides" button instead of the section for Prior Year Unallowed Credit (as Lacerte would treat your entries for §41(g) credit as ***not*** being subject to TMT limit).

The carryforward credits will now show up on a separate Part III with Box C checked and limited on Part II.