Here is possible paradigm of the verb 'to be' in PIE; I wonder if I can account for all the reflexes in the daughter languages.
You will notice that there is no intial *h1; indeed, this is the point. Now then, on to some reflexes.
This paradigm accounts for the Latin forms quite nicely; *esi > es; *esti > est. For the 3rd person plural, Palmer's argument (see this post below) still holds; *s-enti > *s-onti > sunt. Then, the first person plural was created by analogy to the third person plural *smes > sumus and, from this, the first person singular was spawned by analogy *esmi > sum. The second person plural was created by analogy to 2nd person singular form. Palmer's account of the development of the paradigm in Latin remains unchanged.
The Sanskrit reflexes can also develop from these roots with ease.
*esmi > asmi
*esi > asi
*esti > asti
*smes > smas
*ste > stha
*senti > santi
No problems here. Same thing with the Germanic forms; in Gothic and Old English, for example, the plural forms lack an initial vowel.
Given this new paradigm, the odd forms out seem to be the Greek and Anatolian forms, which show an inital 'e' in the plural. This, I believe, can be accounted for through analogy; they came about through analogy to the singular. This is not as strange as it may sound. This exact thing (albeit with an 'a' instead of an 'e') happened in the move from Sanskrit to Pali. Cf.:
Skt. asmi > Pali amhi 'I am'
Skt. asi > Pali asi 'you are'
Skt. asti > Pali atthi 'he/she/it is'
Skt. smah > Pali amha 'we are'
Skt. stha > Pali attha 'you (pl.) are'
The third person plural remained without the initial 'a'.
I have yet to see if I can account for reflexes in Balto-Slavic from the new paradigm. More, perhaps, on this later.