Stuart the way vac motors are set up compared to a vac blower then the TM will out suck a porti anytime, the reason most Scorpion owners think that it as powerful as a smaller TM is because they have just upgraded from a smaller machine, the figures can be hype the proof is when you start to clean.
My Boxxer has 400cfm airflow the same as a Scorpion but I know that when the wand hits the carpet that it will out suck the scorpion hands down, the figures are only good when the wand hits the carpet, the reduction (as I've been told independantly) for a porti will be that it reduces to about 50cfm where a TM to 100cfm (without modifications) although they may add more vac motors there is only so much a vac motor can do with so much current going through it, that's why engines were and blowers were introduced.
Shaun