Cap'n
Rollers, without an add on unit do not
offer enough resistance to build strength.
Yes, smaller diameter drums offer more resistance
as does letting air out of your tires, but is
it enough to build leg strength (as opposed to
leg speed)? I don't know, but I think not.
I think for a new roller rider, a resistance unit
is more trouble than its worth. Lord knows its difficult
enough to really get the hang of rollers without
the added effect of resistance. Its really the speed
(centrifigal force) of the wheels that keeps you upright
on the rollers, that and a smooth pedal stroke.
I'm of the opinion that its difficult enough initially
to maintain a smooth pedal stroke without
having a resistance unit in play.
Let me ask, could you ride rollers with a resistance
unit when you first started on rollers? I know
I sure could not have.
As I said, I have both types of units, use the
rollers for cadence, leg speed, balance etc.
Use the fluid squared for strength. Of course this
means either 2 sessions/day or varying them on
a day to day basis.

Just my $.02 worth,
Marty