To start, I have a Felder CF 741. It is a combo machine, which is basically the K 700 Professional saw/shaper bolted to the AD 741 jointer/planer. The saw table is changed a bit to use the jointer surface as the table. It has the 2500mm sliding table, which is a bit over 8'. I can rip a full sheet of ply using the carriage. It also has the 2600mm (102") crosscut fence and outrigger. That gives capacity to crosscut a sheet of ply anywhere you want. The saw has a 7.5hp motor and a belt driven scoring blade. I use 12" Forrest blades mostly. I have a few Felder branded, which are Leitz, that are also good, but prefer Forrest.
The machine includes a nice shaper, which pops up right behind the saw blade. This lets you use the sliding table to on the shaper, which is a great feature for many things. Raising panels or tenoning for example. The shaper has easily interchangable spindles and is powered by a separate 7.5hp motor. I have three, one common metric and the common standards. Speed is easily adjusted by the turn of a dial. I have the power feeder that swings up, and can be used over the saw, shaper or jointer.
The jointer/planer is 410mm (16.1"). Mine has four straight knives. The spiral cutter was not avalible until a week or so after I bought my machine, or I would have bought it. There is nothing wrong with the straight cutters, just would have liked to try the spiral. The jointer/planer is powered by a third 7.5hp motor. I like to swing the feeder over the jointer outfeed bed and use it to face joint. It makes a job that gives me the hebejebees into something fun. I did buy the mortising table.
Changeover from jointer to planer takes about 30 seconds, the power height adjust makes it easy. You can run one motor at a time, and you have to select which. The motors all have braking that stop them very quickly. The saw blade stops in about 3 seconds, a big shaper head takes longer.
Several things I've noticed in operating this, it radically changed my work style. I am much faster now than with American style separates but it forces you to think a bit to avoid unnecessary changeovers. If you are not ok with that, you will probably not like a combo machine. One constant question I see deals with ripping. Having the sliding table doesn't necessarily change how you rip, if you don't want it too. You can use the fence just like a unisaw if you want. What it does do though, is give you the option of having the board ride on the slider instead. Most of the time I use a combo of that. I let the table float, and use the rip fence as a guide. The table just slides along with the board until the end of the cut, and I put a little down pressure on the board to make sure it stays in place on the table as we finish passing the blade. You can also clamp to the table, or use an edging shoe to hold the front end. The difference between a slider and regular saw, is only that you don't have to use the rip fence. Think of it as the ultimate taper jig at times.
Most of my work is solid wood, but I bought the machine to handle ply sheets too. My shop is a standard 2 car garage, and the Felder sits at an angle in the middle of the room. Another misconception is how much space they take up. Yes, sliding an 8' long piece of ply will move the table 16', and you need a few extra feet behind it to stand. However, you can get its footprint down to 6 1/2' wide, and 8' long at rest. The outrigger comes off easily. I leave mine on most of the time, but to swing it full stroke, I have to wheel a couple portable tools out of the way. I can't imagine why I'd would want a shorter table, but I know some do, for good reasons.
If I did it over, I would have bought it sooner. It's that good. I am building a new shop, and with the more space, I can see how having the jointer/planer separate from the saw/shaper would be beneficial. I would however buy the exact same machines. I have used the mortising table several times, and it is quite frankly, kind of a pain to set up. I would buy a separate mortiser rather than the add on. Dominos changed the game on loose tenons honestly.
Something to be aware of, Felder machine accessories which there are a bunch of, are not cheap. Nothing about it is I guess. They are usually Aigner made components and they may be sourced else where. Leitz makes a bunch of Felders tooling. This is all top notch stuff, and I bring it up to point out that a Felder fence is kind of like a Beismeyer and clones here. It interchanges with many other manufacturers products, and is industry standard components. Blades and such are easy to source.
I didn't want to write a book, sorry, hope that answers some of the questions. I started typing this earlier, so the actual experts have probably already done a better job than me.