Are the health plans really equivalent (besides premiums/deductible)? No difference in coverage or co-pays?
There's three big things here:
(1) premiums deductible/tax free?
I think the marketplace plan is deductible only if you itemize deductions and incur significant medical costs- someone else correct me if I'm wrong -
http://www.forbes.com/sites/kellyphillipserb/2012/11/26/tax-breaks-for-medical-expenses-under-obamacare/. So advantage workplace plan (assuming you can make pre-tax payments for the $1500 of premiums).
(2) difference in premiums
Immediate $1200/year savings for employer coverage
(3) tax savings of the HSA
$3,300 tax free in and out - the tax savings really depend on your tax bracket, much like (1).
Eh...depends on your tax bracket and if you itemize already. In my case, they'd end up being roughly equivalent in terms of tax savings and I'd choose the workplace plan due to the lower deductible.