I'm all the way to Moreland & Fleischer's Unit 2 (whoo-hoo!), and have noticed a discrepancy in its Subjunctive Perfect Active forms and those of another couple of books I'm consulting (e.g., an old Jenney, I believe). M&H don't have macrons on the initial -i of the suffixes:
Whereas other books say the initial i is long, and so show macrons for -eris, -erimus, and -eritis. Without the macrons most of these forms collide with those of the Future Perfect Indicative Active.
Is this a change between an earlier form and a latter classical form, or different scholarly opinions on what the vowel length should be, North Latin and South Latin, or what?