Compression test results: should I keep or sell?

I have an '07 6MT with 97,000 miles I bought about 6 weeks ago. A couple weeks after buying it, it started to get hot and humid here. I began to notice the engine losing power after crusing on the highway for 30 mins or so. So hoping that it was something minor I did the following:

Checked spark plugs (like new)
Checked air filter (like new)
Cleaned MAF sensor
Oil looks good

So took it into Mazda today and here are the compression test results:
(All readings are @ 250 rpm)

Front rotor:
7.2 kgf/cm2
7.2 kgf/cm2
7.3 kgf/cm2

Rear rotor:
6.9 kgf/cm2
6.8 kgf/cm2 (failed test)
7.1 kgf/cm2

So it was only barely under the minimum allowance for 1 of 6 readings.
The tech said he recommended a new engine, new coils and wires, and new cat (because the previous owner installed a magnaflow exhaust with what the tech considers a "small" aftermarket cat.)

So I'm wondering if I were to replace the cat, coils and wires, how long would this engine last? What's especially frustrating is that the 8 year warranty expired last Feb. 24...about 4 months ago.