I began trying to signup on healthcare.gov at midnight on October 1. I work with computers, so I can generally get through an online form. This was not the case for Healthcare.gov. Despite repeated attempts and multiple calls to the help desk, I was never able to successfully complete an online application. However, I was able to register easily through the 800 number. Ultimately, I decided to keep my current COBRA coverage as it was a bit less than the comparable unsubsidized options.
I also assisted my 28 year old son with his application. He could not successfully complete the online application, but easily registered through the 800 number around the third week in December. We mailed in his first month premium and he has coverage starting January 1. We received his insurance card on January 11th. His old insurance was a catastrophic plan with GoldenRule for approximately $160/month. The full price for his new insurance with Innovation Health is $171. Because we are in a non-Medicaid state, he currently is not elegible for any subsidy (income is too low). I anticipate he will eventually qualify for a federal subsidy which would lower his monthly premium to $34.
If his state does not expand Medicaid and your son's income is still below 138% of PL next year, then overestimate his income for the application. That will get him the subsidy and there will be no penalty for over estimating.
Also, I'm a retired doc. My old practice was very large and very well respected and we were contracted with the state/county version of Medicaid for a given number of patients every year. The care that we provided was irrespective of insurance status. We had very little trouble refering Medicaid patients to most of our regular specialty providers either.