I’ll trade the hammer for a qualified GC or PM and for three more properties cash flowing (and appreciating) at $350/month.

Only the subs need to be licensed in their trade.

Trading SS/Medicare taxes for SEP contributions not sure it would make sense. 

Single, multi, commerical..The new property I want to exchange for is worth $2.5M.I read online that as long as the like-kind property is used for rental, business or trade, or investment then it is suitable for the exchange.I'm still not clear about finding a like-kind property.

A huge audience of non-performers.People who save and invest, as well as learn their trade know they're are no shortcuts to real estate investing. 

Sure, the cash flow on them and ultimate returns may not be as high because you're paying more for them, but it's all a trade-off.I think they're great for newbies, so much so I wrote an article about it-https://www.biggerpockets.com/blog/turnkeys-for-ne...And as far as whether they are good investments, all of mine have been very profitable.

He suggested a potential trade for repairs for rent.

By definition of CAP rate, a stable rental building is currently trading in many places between 4% - 8% CAP. 

Are you nee and attempting to trade time for experience?

You have to make them aware of the other potential consequences they have no clue about.