I thought I'd throw this one out and let the list dissect it.  Let's do a
tentative cost comparison of two engines, the TIICO and Boston Bob's
Big-Valve Boxer.  Not everything below is 100% accurate, so feel free to add
and change, but let's keep it practical.

Boston Bob's Big-valve Boxer:

$3050 + core
likely to install yourself
shorter wait for motor
more grunt
more reliable than factory WBX (?)

Tiico:

$4000 plus
sell engine to recoup some cost
wait 6 weeks
tougher to install and set up - more $$
high-revving
tough as nails

Now, based on an average gas mileage of 20 for TIICO, assumed 15 (does
anyone know?) for Bob's motor, gas cost of $1.40 per gallon and 12000 miles
traveled a year, Boston Bob's Big-valve Boxer will cost $280 more in gas per
year to operate.  This means it will take about 3 years for Tiico's improved
mileage to pay off.

Have at it!