jeff,
i'm glad things have been going well for ya with the vents, and am happy to have been of help

paul,
when ya refer to stove hood vents, this is a completely different animal when compared to bathroom and dryer vents.
yer in the great white north in canada somewhere, yes?
i'm not familiar with the laws regarding this type work there, but here in the states, one must be certified and carry bookoo insurance. besides, no one would ever hire you to provide hood service, without the proper credentials!!
the machines at nikro ya listed are very good but not needed as jeff can attest to. a quality hepa or micro filtered shop vac will suffice very well.
there are some single motor shop vacs with 200cfm's and can be found at lowes or home depot.
the solid core system, while it is quite ridgid, and not as flexable as the standard rotary brush system at nikro, it is much stronger, and can also be used to clean air ducts, central vacuum systems, and rain downspouts on homes or businesses!
while cfm and water lift are very important in water extraction, such as in carpet cleaning, when it comes to dry removal, such as dryer vents or air ducts, cfm is the more important.
although the 88" of lift seems weak in the nikro, if ya put yer hand over the hose end, you'd feel how strong it is.
the suction ya feel on yer palm is the vacuums creating lift. once ya remove yer palm from the hose end, that rush of air ya hear is the cfm.
one of the machines i have produce roughly 2200cfm's, and when i connect a booster, it produces just over 3000cfm's!!
whats funny is the rated lift on that cfm production is 6 static inches!!
sounds totally stupid, yes?
the air flow on that machine is fantastic, and has enough power to slam shut all the doors in a home!!
any 3 vac machine will have 2 power cords, and will require more than 15 amps!!