There have been 2 previous models of Rotex sanders: the original Festo RO150 was a pretty good, heavy duty (almost) all alloy model, replaced in the late 80s by the RO150E, with ABS/FRP/Nylon plastic gears & casing/s.
I really like this model. It is smaller, lighter, but sufficiently powerful to perform well. Somewhat sticky & reluctant to change modes, the only real maintenance issue was a tendency to strip the drive gears from extended hard use in forced rotational (RO) mode. Not the outer crown wheel (although this does wear too), but the inner planetary gearset.
What makes this particular model stand out is the ability to choose alternative pads from a variety of manufacturers due to its more common industry standard format & mounting. Saving literally hundreds (possibly a thousand or more) of operators' dollars over the tool's lifetime. The central 8mm mounting grub screw will sometimes seize in place, making pad exchange problematic due to the combination of the ingress of resinous dust, swarf & heat. Easily eliminated by the regular loosening & tightening of said screw with the onboard hex key.
The latest model's bayonet pad mounting system has been problematic, with the mounting system suffering from premature wear & looseness, allowing the pad assembly to repeatedly drop off. This problematic bayonet mounting seems to suffer most in the largest 150mm version, locks the unfortunate user into unnecessarily expensive OEM replacements only and becoming increasingly insecure as the tool ages. One user I know has resorted to using "No More Nails" adhesive to keep his pads securely affixed to his Rotex sander long before the velcro hook surface of the pad wears out! In my opinion using a bayonet mount benefits the company far more than the user: designed more to lock the user into stupidly expensive OEM replacement and otherwise needless bayonet repair than any tangible time advantage in pad replacement. The latest multi-hole pads at least can accomodate the latest mesh abrasives better than previous versions do.
This latest model has the advantage of interchangeable pad guards available to reduce peripheral pad wear. Neither of the previous models featured pad guards.
Despite being much lighter than the previous 2 models, even the latest Rotex sanders are pretty heavy beasts & also feature fairly awkward ergonomics & operation. They just seem to get very tiring to use for extended periods than more balanced alternatives. Extremely so with verrtical and overhead use. Just about any belt sander, especially the Holz-Her, Metabo, AEG, Atlas Copco, Wolf, Wurth & Festo/ol clones (when fitted with their fabulous sanding frames) will be faster and significantly easier to use horizontally than the rather awkward angular Rotex sanders. For large scale substrate flattening of slabs etc., the increased mass and inertia of the biggest 4" x 24" belt sanders are a positive advantage. A big, heavy Holz-Her type framed belt sander won't "fight back" like a Rotex in RO mode does. Much smoother & rapid progress, far superior flatness and surface finish is the result.
Mirka's DEROS 680CV, with a combination of a much larger (by 60%) 8mm random orbital pattern will also provide rapid abrasion with a significant reduction of swirl and gouging than a Rotex in ROT mode: even in EX(zenter) mode it can scratch badly if not gripped tightly. They (Mirka's DEROS range) also weigh less than HALF the mass of a Rotex, & provide far superior, comfortable balance & ergonomics to boot. You will always get a better finish from just about any inline Random than an offset gear or belt driven Rotary/Rotex sander.
Rotex sanders (& their Makita & Robert Bosch competitors) are good, versatile sanders. But also quite a bit rougher & cruder in operation than the abovementioned alternatives.
PS. Given the stated quantities involved, would you perhaps be better served with a dedicated self-feeding drum-sanding "thicknessing" sanding machine to afford an element of uniformity? The time saving to process several thousand board feet of hardwood, especially processing BOTH SIDES would be substantial, & probably much more cost effective in terms of consumables too.