I bought the Bertha when it was new and not well tested. It cost $550 and was hard to put togather.
My machine is the Viking Sapphire with the 10 inch throat so required a bigger cabinet.
Bertha has extensions on both sides and back but they only fold up not down so you have to lower the machine to close the sides. The back extension lays down and has a leg to prop it up with. You need lots of room for it as open it is 7 ft long. It is great for quilting and I love it.
I think Sew Esi now makes a table for larger machines so would be alot cheaper.