LARTC - Mar 2007 - HTB: is root a class really necessary?

i have been using a HTB setup for almost a year now, and i have created it 
w/o a root class.
i ll try to draw it here:
1:0---1:3---1:30-local small traffic
 	 ---1:31-local rest of traffic
    ---1:5---1:5xxx- classes for the trafic that comes from the metro part 
of the ISP that i use
    ---1:7---1:7xxx- classes for the trafic that does not enter the 
previous 2 classes(the internet traffic)
    ---1:4- default class

all these classes: 1:3, 1:5, 1:7, 1:4 have as their parent the root qdisc.

the motive behind this setup is that i don t want any borrowing between 
these classes

as for the  filters, i have 2 of them
-a prio 1 filter, atached to 1:0 that sends
 	local traffic to 1:30,1:31;
 	metro traffic to 1:5
 	internet traffic to 1:7xxx
-a prio 3 filter, atached to 1:5, that sends traffic to 1:5xxx

by using this setup of filters i reduce the number of tc commands to be 
given in order to create the filter

i ask this, because in all the examples i saw, all scripts use a root 
class, between the root qdisc and the other classes.
also i saw that many examples atach filters directly to the root qdisc.
my seup seems to be running well, but i want to know if using a root 
class, or filters of the same prio will improve my setup.

tnx