There is a long answer for this...but I am going to give you the short one. Plans are coprighted (Google "copyright architectural plans") and you cannot buy plans and alter them without buying the rights to alter them (or create derivative works, in legal speak). You also cannot take a sketch plan you like and give it to an architect to re-create without paying for that right.

The plan you posted has some copyright information in the FAQ, it can be read here (attached). It looks like a reproducible set gets you a copyright release. That is the avenue you would want to pursue if you really like most of this plan.

Here is a link that might be useful: FAQ

purchased the CAD version, figured that was probably the best way to go.

Has anyone purchased stock plans? were there many modifications to meet your local building code?

The two options you presented would result in the same end product. An architect would create his/her own CAD drawings regardless of what you give him/her. Starting with an existing set of CAD drawings might or might not save time but in the end the architect has to create something he/she can put their name on. Personally, I find it a waste of time unless the project is a renovation and someone has measured and drawn the building accurately.

Very little information would survive the transition for reasons too numerous to mention. It is virtually impossible for a set of drawings from a plan mill to be appropriate for all locations, site conditions, and codes not to mention regional detailing preferences. The Internet might have shrunk the US metaphorically but the regional construction conventions have not followed suit.

IMHO when you hire an architect it is foolish to not take advantage of their talents but I may be prejudiced after 40 years.

I can't comment on US plan mills. Their products are peculiar to the US, generally fitting neither tastes nor lots in Ontario's Golden Horseshoe.

What I've done is collect local subdivision floor plans, then have them adapted to the site and make changes as necessary. Frequently, the changes are so extensive that I've driven by the subdivision homes and don't recognize them. Though that also has a lot to do with the inferior materials and workmanship they display vs. my adaptations.

I'm starting with searching the internet, and have narrowed it down to a few stock plans I like - 1 being the main one. They ALL have the same basic footprint, just lightly different setup's. I plan to get graph paper, and draw out the basic footprint and make it my own, with different parts from each plan I like. I'll bring it to an drafting firm or an architect (probably a drafting firm.. need to research this yet)