I understand this thought process behind your argument, but I have always found it disingenuous at best.
The problem is that embryonic stem cells were first isolated in November 1998. That gives adult stem cells a 30+ year head start in research. Naturally adult stem cell research is more advanced and would be more likely to produce results.
When it comes to funding, the business world only seriously invests its own cash when there is a positive expected return. Did we see large business investment in adult stem cell research in the 1960s, or was it largely government funding? Do you expect businesses to fund work that may or may not pay out in 30 years?
In any case, this is a moral argument, and we should keep it as a moral argument. I think Bill Bennett made a similar argument - don't mix economic arguments with moral ones, as you can end up with silly looking assertions...
They've been experimenting on mice embryonic stem cells for nearly 30 years now, that is a fact. 1998, I believe was year in which the first actual experiments on human embryonic stem cells took place. Now who is being disengenous with the facts?