How can I evaluate the contribution of Ariel and Caliban for actors in a production of The Tempest in the 21st century and compare this with its original performance in 1611?

Produced at a time when the masque was in style and extremely popular, Shakespeare's Tempest has many of the elements of a masque, and in 1611 it was performed as such. However, whereas a masque was often a performance that celebrated authority, The Tempest presents vulnerable qualities in authority. The theatrics of Prospero (who is assisted by Ariel and other spirits), the vanishing banquet, and the masque of goddesses and lovers playing at chess all serve the former duke in making amends for the sins of the past. Ariel is released and Caliban "seek[s] for grace" while Prospero prepares his own spirit for death. 
By conjuring up the storm with his magical powers, Prospero finally impels his brother Antonio to repent. However, Antonio fails to follow the lead of Alonso because he does not ask forgiveness. Sadly, with all his powers and his control over Ariel and Caliban, Prospero still cannot generate a conscience for Antonio. However, at the beginning of Act V, Prospero begins to perceive that true humanity is a matter of practicing strict Christian virtue rather than trying to impose one's will on others: 

Though with their high wrongs I am struck to th' quick,
Yet with my nobler reason 'gainst my fury
Do I take part. The rarer action is
In virtue than in vengeance. They being penitent,
The sole drift of my purpose doth extend
Not a frown further. Go release them, Ariel. (5.1.23-31)

A contemporary performance of The Tempest would differ from that of 1611 as it would probably not focus upon the masque. Instead, the motif of European colonialism and its evils might be exposed. In this play, Shakespeare responds to the exploitation of men that exists with colonialism. Caliban, who feels that his land has been stolen, tells Prospero, whom he perceives as an oppressor:

This island's mine by Sycorax my mother,Which thou tak'st from me. When thou cam'st first,Thou strok'st me and made much of me ...... and then I loved thee ...Cursed be I that did so ...For I am all the subjects tht you have,Which first was mine own king; and here you sty meIn this hard rock, whiles you do keep from meThe rest o 'th' island. (1.2.331-344)

One could argue that The Tempest refutes the idea of the "noble savage" and shows how colonialism robs natives of ownership and, instead, subjects them. Certainly, modern productions of The Tempest often portray the evils that have developed from Europeans having colonized areas and subjugated the native people. 
 
In a modern production of The Tempest, therefore, the focus of the drama may well center upon the exploitation of Ariel and Caliban rather than upon the efforts of Prospero to right the wrongs of his kingdom.
http://www.columbia.edu/itc/lithum/gallo/tempest.html