Stability when anchored was fine on the 12', while the 8' swayed too much for me. Sold the 8' cause the oars banged my knees and I didn't have a need or desire to use it as a kickboat. The 12' version I sold to a buddy who wanted to add a frame for his kids to join him. The 8' I sold to another buddy who wanted to use it as a kickboat (plus he is 10" shorter than me). I have a 11' Outcast with similar diameter pontoons and a better frame layout, so no need to keep the 12' around (I also have a flyfishing raft). I also, at one point, had a Jacks Plastic Weld 10' w/ 19" diameter tubes with an AIRE (recretec) frame. I also sold it as it was very similar to my outcast PAC1100 but without leanbar and standing platform; it was sold on Craiglist to someone who wanted to do overnight whitewater trips.
On both the 8' and 12' Maxxon's there was not enough clearance for me to comfortable operate a 3 hp or trolling motor (ie seat was too close to the back of the frame). Also battery storage was an issue. I have better boats to motor in the lakes.
PS Anchor stability is just a function of width of frame, along with tube diameter (ie displacement). A 12' tube with 18" diameter anchors pretty much the same, regardless of brand (most frames are pretty much same widths).