The advantage of the variable steed normally means that you can spin a
larger than 1" diameter bit with out having to worry about the tip speed of
the bit being too high. You simply slow down the speed to a safer speed.
That said, with a router of that size, you are not going to want to be
spinning the larger bits anyway as the router does not have the power to
comfortably perform the task and especially on the biggest bits.

That said, this router will be a good size for cutting with the smaller
profile bits and a great size for cutting dove tail joints. Variable speed
comes in handy regardless of the size bit your are spinning when you work on
different woods. Since many woods are prone to burn more easily than
others, slowing down the bit speed can help to prevent burns. Also many
woods cut better and cleaner with different cutting speeds. So I would
recommend getting the variable speed.

Lastly, the current Wood magazine had a review of several routers in this
class that come as fixed base and plunge based kits. IIRC Bosch came out on
top followed by DeWalt and Makita. and lastly the 690 series PorterCable.
If you are wanting to be frugal with your purchase, the Porter Cable is a
safe bet but the design is becoming dated and out paced by the competition.