I have no experience but have seen and examined the Sand Flee a commercial version of the V-sander at WW shows for years.
First, you need to ask yourself what you want a sander to do. Units like the Sand Flee and V-drum Sander, are VERY lightweight and usually powered by a fractional hp motor. They get by with this because the diameter of the drum is usually much smaller (2" - 4") than typical drum sanders (6"). They can be useful sanding small items and for veneer work but are not much good with case work, tables, cabinet doors, etc.
I can't say, because I have never used one, but think it would be extremely hard to sand a flat surface so it stays flat, using only hand pressure to hold the stock against the drum and feed it. Other drum sanders have conveyor belts, pressure rollers,. etc.
The Stock Room more advanced "Flat Master" model gets pricey really fast- a 24" Flatmaster is $819 and you still need to buy a motor. They recommend a 1/2 hp motor for the 24" and 30" Flat Master. Compare that with a 5 hp or larger on a 24" Grizzly dual drum sander with conveyor belt feed and separate feed motor that you can typically find used for around $500 - $600.
If you try to build the bigger V-sanders, you need to fabricate a lot of the machine, stand, and still need to buy the motor (their kit comes with a drum, bearings, 2 balanced pulleys, Linkbelt, plans, and sandpaper). You end up with a homebuilt machine that may or may not be accurate, able to handle the work, or durable. The cost and the time building one vs buying a used drum sander with conveyor, may not be much difference, except a real drum sander will work much better.
As you may know I am a big fan of tinkering and DIY, but would not waste my time on one of these, unless I was doing veneer work.
