pros and cons to every one of the agitation machines so it might be difficult to pick just one to recommend , i used a rotowash for a few years for most types of carpet agitation , works fine really , id say not a massive difference with a tm4 , but the tm4 would be slightly more specialised for carpet .
I have a tm3 and a couple of rotarys which cover most situations , depends on you budget , but a good condition used victor 17" combined with soft and hard brushes and white to red floor pads for various carpets could cover all situations for little money .
The tm3 is great in that you never ,dont feel like carrying it a distance from the van or up those stairs . And i find it great on stairs also . If you have the budget and dont mind the extra weight for carrrying the tm4 with be quicker in bigger room situations .
If i had to choose two ... i would say tm3 is good value at the <700 price from cleansmart and world of cleantalk . Considering the americans get totally shafted at around 2000 usd for their brushpro badged version . That a rotary for a couple of hundred will make like easier for you in any carpet situation + hardfloor with the rotary .
