Engine Rebuild?

[Jacob Michaels]

I have a continuing problem (3 years) with warm-start and WOT smoke, with 
accompanying oil consumption of 1 quart every 500 miles.

Reputable mechanic here in Portland, OR feels that the leakdown test shows 
the need for some ring work (values ranged from 12-20 %) and that it 
probably is not the turbo as these symptoms have  lasted for an extended 
period of time, and when turbos go bad they go bad quickly.

At the same time he said the bottom end doesn't seem in really that bad 
shape, and that the oil consumption could be multi-factorial.

Is it time to tear the engine down to find out?  Car has 149K.

Jacob