One's a static ability, and the other is an activated, mana, ability. So if the card gets Encrusted the latter ceases to work but the former is a-okay.
If you control Sunglasses of Urza, March of the Machines, Xenograft set to Saproling, Life and Limb, and Caged Sun set to red, then Sunglasses of Urza would also be a land and with "{W}: Add {R} to your mana pool." it would produce an extra mana from Caged Sun.
I'm sure that must be why they haven't changed it. [/sarcasm]
I added a cycle of artifacts for all ten pairs in my set. But I was thinking, with more than one in play, one is going to shift the other. With 5 in play, all mana can be spent as mana of any color. If I use the sunglasses wording, then it creates a strange situation where mana counts as every color at the same time.
EDIT
Broken. Just noticed that creating such a cycle of artifacts effectively breaks the color pie.
Whether or not it is breaking the color pie (I don't really think it is), why would you spend ten card slots on a full cycle of Sunglasses of Urza? Just do a personal Mycosynth Lattice. With cards like Chromatic Lantern at three mana, I think this would probably be fine, if possibly a little weak:
Chromatic Sunglasses 4 Artifact (R)
You may spend mana as though it were mana of any color.
The problem with an artifact that makes any mana be of any color is that it's essentially overwritting the colored mana costs of all cards. Mycosynth does that at the cost of removing all card's colors and making all permanents artifacts.
Mycosynth Lattice making everything artifacts is more often an extra benefit allowing for weird combos or at the very least interactions with cards like Shattering Spree. Chromatic Lantern already mana fixes all of your lands and even accelerates you a little. Color fixing has always been a territory of artifacts, so that is fine here. And this isn't free. It costs mana and takes up a card slot in your deck.
I̟̥͍̠ͅn̩͉̣͍̬͚ͅ ̬̬͖t̯̹̞̺͖͓̯̤h̘͍̬e͙̯͈̖̼̮ ̭̬f̺̲̲̪i͙͉̟̩̰r̪̝͚͈̝̥͍̝̲s̼̻͇̘̳͔ͅt̲̺̳̗̜̪̙ ̳̺̥̻͚̗ͅm̜̜̟̰͈͓͎͇o̝̖̮̝͇m̯̻̞̼̫̗͓̤e̩̯̬̮̩n͎̱̪̲̹͖t͇̖s̰̮ͅ,̤̲͙̻̭̻̯̹̰ ̖t̫̙̺̯͖͚̯ͅh͙̯̦̳̗̰̟e͖̪͉̼̯ ̪͕g̞̣͔a̗̦t̬̬͓͙̫̖̭̻e̩̻̯ ̜̖̦̖̤̭͙̬t̞̹̥̪͎͉ͅo͕͚͍͇̲͇͓̺ ̭̬͙͈̣̻t͈͍͙͓̫̖͙̩h̪̬̖̙e̗͈ ̗̬̟̞̺̤͉̯ͅa̦̯͚̙̜̮f͉͙̲̣̞̼t̪̤̞̣͚e̲͉̳̥r͇̪̙͚͓l̥̞̞͎̹̯̹ͅi͓̬f̮̥̬̞͈ͅe͎ ̟̩̤̳̠̯̩̯o̮̘̲p̟͚̣̞͉͓e͍̩̣n͔̼͕͚̜e̬̱d̼̘͎̖̹͍̮̠,͖̺̭̱̮ ̣̲͖̬̪̭̥a̪͚n̟̲̝̤̤̞̗d̘̱̗͇̮͕̳͕͔ ͖̞͉͎t̹̙͎h̰̱͉̗e̪̞̱̝̹̩ͅ ̠̱̩̭̦p̯̙e͓o̳͚̰̯̺̱̰͔̘p̬͎̱̣̼̩͇l̗̟̖͚̠e̱͉͔̱̦̬̟̙ ̖͚̪͔̼̦w̺̖̤̱e͖̗̻̦͓̖̘̜r̭̥e͔̹̫̱͕̦̰͕ ̗͔̠p̠̗͍͍̱̳̠r̰͔͎̰o͉̥͓̰͚̥s̟͚̹̱͔̣t͉̙̳̖͖̪̮r̥̘̥͙̹a͉̟̫̟̳̠̟̭t͈̜̰͈͎e̞̣̭̲̬ ͚̗̯̟͙i͍͖̰̘̦͖͉ṇ̮̻̯̦̲̩͍ ̦̮͚̫̤t͉͖̫͕ͅͅh͙̮̻̘̣̮̼e͕̺ ͙l͕̠͎̰̥i̲͓͉̲g̫̳̟͈͇̖h̠̦̖t͓̯͎̗ ̳̪̘̟̙̩̦o̫̲f̙͔̰̙̠ ̹̪̗͇̯t͖̼̼͉͖̬h̹͇̩e͚̖̺̤͉̹͕̪ ͚͓̭̝̺G͎̗̯̩o̫̯̮̟̮̳̘d̜̲͙̠-̩̳̯̲̗̜P̹̘̥͉̝h͍͈̗̖̝ͅa͍̗̮̼̗r̜̖͇̙̺a̭̺͔̞̳͈o̪̣͓̯̬͙̯̰̗h̖̦͈̥̯͔.͇̣̙̝
If you control Sunglasses of Urza, March of the Machines, Xenograft set to Saproling, Life and Limb, and Caged Sun set to red, then Sunglasses of Urza would also be a land and with "{W}: Add {R} to your mana pool." it would produce an extra mana from Caged Sun.
I'm sure that must be why they haven't changed it. [/sarcasm]
EDIT
Broken. Just noticed that creating such a cycle of artifacts effectively breaks the color pie.
Chromatic Sunglasses 4
Artifact (R)
You may spend mana as though it were mana of any color.