Kindof wanting to ditch the Cranial Plating & Prototype Portal to get some more reliable creature protected and/or card draw/counter ramp. Any ideas?

At the moment Prototype Portal tends to be too slow. Cranial Plating is good but really isn't the cause of me winning games - that tends to come down to the Steel Overseer and my Proliferate cards. I mostly win by a horde of overwhelming creatures as opposed to one boosted one (I know I can splash black to help the plating be more useful, but keen to hear other options also)

I'd run Expedition Map 's to help the Urza lands

As well as Blighted Agent with Bioshift as an additional win con

the urza land's are a nice to have. but you don't play many expensive cards. it looks like you will get the lands eventually on turn 5-6 or sooner if you're lucky. but i would replace them with Academy Ruins, Blinkmoth Well, Blinkmoth Nexus, Buried Ruin, Darksteel Citadel, Desert, Dread Statuary, Ghost Quarter, Inkmoth Nexus, Phyrexia's Core and others...
http://magiccards.info/query?q=o%3A1+c%3Al+f%3Amodern&v=card&s=cname
i also would replace the Tezzeret's Gambit with Mana Leak or Fuel for the Cause. so you can t3 or t4 play a land and say go. and have options with a counter spell, mirrorweave or if you don't need them you can cast Steady Progress eot.
nice deck, +1

Academy Ruins looks pretty inviting, though I have to see how well I go without the Urzas - currently they help quite a bit with all that card draw I have.

Either way i'm thinking I need to drop 2 islands to get down to 20 land

you chould also replace the lands with myrs. they would be mana generators as creature. so they will also get counters