I think it really depends on how you are going to use the ebike (steep up/down dirt trails, paved bike trails, side and main roads, work commute, weekend fun rides, etc...).
I have a Class II Radrover 4" fat tire mountain bike (750w rear hub motor, 48v 11.6Ah battery, PAS 0-5, throttle with on/off switch, 20 mph max speed). The twist throttle for the Radrover can deliver up to the full 750w the more you twist at any PAS level (even at PAS 0). Some ebikes can only deliver throttle power up to the current PAS level only. I use PAS about 90%-95% of the time. There are situations when only a throttle will work and I'm glad I have both.
I love having the full power on demand for certain situations like:
- tight turns where you pedals might touch/hit the ground and you want to maintain your speed
- riding over or near obstacles on trails or curbs and the pedals would scrap or hit
- need a little extra boost over a short incline or to get across an intersection faster
- if you need to push your +60 lbs ebike up a steep incline or over obstacles
- When you just need a rest and need to coast for a while; but, maintain your speed
- a back up if can't pedal for any reason
Having a throttle saved me when:
- Only had my Radrover for about a week and my left pedal crank fell off at 5:30am when I was about 3 miles from home on my work commute. I didn't hear when the bolt fell off securing the crank, just turned around and put the crank arm in my backpack. I just used the throttle to power home instead of having to push the bike the 3 miles uphill back home.
- My right shoe lace became untied a few weeks ago (again at 5:30am during my work commute). Way to dark to see how bad it was, I just used the throttle to get to more light about 1/2 mile down the road and untangled the mess (unable to pedal because my shoe lace was all wrapped around everything). Good chance I would of walk the bike the 1/2 miles without a shoe if I just had PAS only (double knot for now on).