I owned a portable walking foot machine like this. Here is my take on this type of machine.
First of all it is NOT a true industrial machine. It would be better described as a beefied up domestic machine.
Really, 800 SPM isn't fast at all. This machine isn't targeted at high speed sewing (a high speed machine would be more like 5000 or so SPM). It is intended for ocassional use on difficult to penetrate materials that can easily compress to 1/4 inch or less. If what you want to sew is more than 1/4 inch- it will NOT fit under the presser foot.
These machines are capable at sewing the heavy stuff (less than 1/4"), but they are very unrefined. Since the parts don't have a very high quality fit and finish, these machines don't oeprate smoothly at all. So, there is a great deal of friction at start up for the motor to overcome to get the machine going. This results in difficulty in getting them to start up and sew smoothly without "taking off" at full speed from the start.
The main reason I had the machine was for my DH to make some "guy things" (motorcycle seats for example). I was able to get it to not start off like a race horse, but for DH, the machine had two speeds. - dead stop and full speed. Needless to say, stitch control was an issue for him. This machine was an an older Thompson mini walking foot machine which is on par, quality-wise, with the Sailrite machines (This is back when the Thompsons were NOT made in China and were still checked over and tweaked in Texas before they were sold to customers). IMHO, this Consew would be of a lesser quality and such issues would be magnified.
DH did make his motorcycle seat, but he didn't use the Thompson walking foot machine. He used a Kenmore 158.1753. I used the Thompson for a few projects and then promptly sold it. I still have and use the classic Kenmore 158.1753.
Everyone is 100% about this Consew machne not being suitable for sewing any material that isn't heavy.
For further reading, you may find this helpful:
Industrial, Commercial Grade, Professional, Industrial Strength & More- Sewing Machine Buying Guideexcerpt from that page:
Industrial, Commercial, Professional, Domestic Sewing Machines- Confused???
Should you get an industrial machine? How about one that is “commercial grade” or “professional”. What about an “industrial strength" sewing machine? What do all these terms really mean and, what's the difference between them? It’s all so confusing!!