I took a quick crack at the question and thought I would post my answer here in case some are interested. Probably missed some things but it's certainly food for thought.

A good question and I for one like Silver Wheaton and their business plan. In a higher silver market it will do very well. If you use the comparative chart from the latest TD Bank highly professionally done presentation you will see that ECU has a resource potential just behind Silver Wheaton in the graph. But when you compare market caps Silver Wheaton is at approximately $3.7 billion and ECU at approximately $490 million.

Now I recognise Silver Wheaton has no capital costs but their costs are sunk in the acquisition of silver ounces plus the cost of money to carry this purchase, not small sums I might add, in fact much larger sums by many multiples for what ECU would spend on a mill or exploration. I also recognize their present resource is at a higher level of confidence. They also don't have the risk of production but do have the risk of non-delivery of production.

All told I beleive ECU will deliver a billion ounce resource or higher at a much lower sunk cost than Silver Wheaton spent acquiring their ounces. The question than becomes how much do you discount the ECU market cap given the present circumstanes and I will leave that for you to decide but I will suggest it should be no where near the present 7.4 to 1 ratio in favour of SLW.

Long term ECU has the potential to have a similar market cap to Silver Wheaton, a very powerful motivator to own the stock for me but you'll have to decide for you.

BTW, it wouldn't surprise me to see Silver Wheaton trade at $30 over the next year and my guess is if SLW doubles that ECU will go up 3-4 times in value and still have lots of catchup room as further ounces are converted to higher confidence levels bring it closer to SLW resource levels. For SLW to go higher now they only have commodity pricing as new deals will be really expensive compared to purchasing at $3.90 per ounce before. I musy say Telfer did a great job though and I have made good money on SLW over the years.