Several weeks back, someone was auctioning off a "Solaris" by ADC (American Dryer Corporation) washer and dryer set. As the washer was "soft mounted" (read: has built in suspension and pump system), all one needed was the space, solid flooring and electrical requirements.
Commercial front load washers fall into two sections: soft mount and hard mount.
Hard Mount: These are the washers one sees at laundromats and most other commercial laundries. They do not have built in suspension systems nor pumps. Rather are bolted into several feet of concrete and literally "dump" water into a sewer line by opening a gravity drain. Wascomat and Speed Queen are common models.
Soft Mount: aka "Home Style" washing machines do have built in pumps and suspension systems (like home use front loaders), but are built to a higher standard. These units are usually robust, heavy and built to anywhere from light to heavy commercial standards. Light being along the lines of a beauty salon, and heavy a commercial laundry whom for various reasons cannot install a hard mount washer.
Both soft and hard mount commercial washing machines and dryers are NOT cheap. A 18lb washer can easily run several thousand dollars. Used commmercial washers and dryers sometimes appear on eBay (sometimes mint in box or lightly used), but unless you live near the seller, shipping could be a problem due to size and weight of these items.
If you want to step up from Maytag Neptunes, and are looking for a good quality washer and dryer, consider Miele. Their largest washer (which is also the entry commercial unit) holds only about 6kg though. Another option would be the Speed Queen "Home Style" line of washers and dryers. The front loading washing machine holds 18lbs of laundry, but has no heater and cycle choices are rather skimpy. Basically a commercial grade laundromat washer for home use. Nothing fancy but gets the job done.
When looking at commercial units, besides the pump/suspension system, pay attention to the electrical requirments. Many units run on 220v/three phase power, even those without heaters.
Reading over your post again, I'd strongly suggest you take a look at the Speed Queen "Home Style" units. They are simple but well built units that probably would work well with your wood framed floor.
Launderess