Okay how's this:
I couldn't find any reviews that stated the actual assist levels. But
what we /can/ do is compare the batteries to a known example.
--------
On this page--
http://www.norcom2000.com/users/dcimper/assorted/inanities/recumbent/moto_bike_page/episode005/episode005.html
is my comparison of the four Bionx setups (different batteries). You see
the first battery noted is the NiMH 24V 8Ah that costs $395 and can
propel the bike about 4495 miles over its (the battery's) total expected
lifetime. (-?-Bionx only suggests 450 discharge cycles for NiMH's but
anyway-)
Now, this page:
http://www.myebike.com/bikes/lite2.html
says that the Giant Lite battery is a 24V 6.5Ah NiMH, and that the
replacement cost is $350. This price agrees with a second place selling
LaFree batteries for $360:
http://www.bernsonev.com/giant-parts-accessories-c-34.html
If we assume that the LaFree motor and battery are no more efficient
than what the Bionx uses, then (6.5Ah/8Ah) x (4495 miles x (500/450
discharge cycles)) miles = 4058 miles total, you should expect to get
from an LaFree battery pack over 500 discharge cycles.
4058 miles / $350 battery replacement cost = $.0862 per mile, or 8.62
cents per mile.... Now look at the fuel costs for the 4-cycle engine on
my page; with fuel at $2.50/gal and assuming 200 mpg, the gas engine's
cost is ~1.25 cents per mile.
Oh, and purchase price?... That's cheaper too. The LaFree bike cost
around $1300, many places report. A gasoline engine kit costs from $150
up to $600 (for the Golden Eagle kit I chose), plus a suitable bike
(which may be as cheap as $100).
If you figure matters on a cost-per-power comparison, the gasoline
engine would come out way on top again. The Bionx setup has a high
"peak" output, but that [most likely] is at zero RPMs. Most of the time,
it doesn't put out more than 300 or so watts, where the Robin 35cc
4-cycle engine (on the setup I chose) will put out ~800+ watts cruising
power (1.1 hp), and can peak at up to 1200+ watts (1.6 hp).
--------
I'd LOVE to see a electric setup (that is available to consumers) and
that can compete on a cost-per-mile with gasoline... but I've done
figures for a few setups that were supposed to be technically
outstanding, and they all still fell /way/ short of what a 4-cycle
engine burning gasoline could do.
~