According to Florida Sairlifts
Curving stairlifts can be the ultimate stair climbing solution if your stairs turn to the left or right. This is true except when an inferior stairlift model is chosen. "Modular" or "Kit of parts" stair lifts are offered for manufacturers convenience and profit not customer satisfaction. The continuous track system of a custom curving rail stairlift should allow the user to travel safely up and down one or more levels without changing to a second stairlift. It should also be compact enough to allow other stair users to walk by without causing any obstruction.
Although a custom curving stairlift is usually the best solution, buyers must ensure that they know exactly where that rail / track will run or you could end up with a costly mistake you can not live with.
Stairlifts claiming to be modular or assembled from a kit of limited parts are not true custom curving stairlifts. They often produce disappointing results such as shown below in the photographs taken of an actual stairlift installation.
This stairlift cost in excess of $10,000 and had to be replaced with a true custom curving stairlift shortly after installation.
Modular curving stairlifts tend to suffer from the following problems:
They require an excessive number of support legs visually littering your staircase with hardware.
These lifts claim significant user weight capacities but are typically very lightly built to save materials cost and flex alarmingly in use.
Often the rail /track does not install close to the wall due to the limited kit of parts available. Wide turns taking up the width of your staircase are normal.
The ride is often rough and users feel every bump of every assembled track joint.
The battery life is minimal with very few journeys possible before a recharge is required.
If the seat leveling system is electronic it can alarmingly allow the seat to tilt downhill if the batteries become exhausted.
Exhausted batteries require an expensive technician visit to reprogram the device leveling.