Sayre Kulp 

I am a big guy (400+ lbs, but actually going down) and I know I need a bike built to support my weight. I spent a lot of time looking over the bikes on supersizedcycles.com and I found the iZize Mt Trailz AL Electric Bike. It looks like it would be the perfect fit for me. I don't honestly know anything about ebikes or what determines a good motor/battery. It says the motor is 450 W from a DC Earth magnet motor and the battery is EV Rated SLA Type Rear Rack Mounted 24V / 10AH Pack. Help me out here, folks! IS that good? Will it give me the torque necessary to help with hills and such?

Allen

An electric bike will be a good bike for helping you get into better shape however it won't be a very good bike for doing centuries or touring.
I don't know this bike I'm going to let the others review it for you.

What I would recommend is use an electric until you outgrow it (no longer feel that you need an assist). Keep it. It will always be a good commuter/grocery getter.
But when you are ready something like the Surly Long Haul Trucker (commonly called the LHT) will be an excellent bike for centuries and touring.

Bikes are very job specific but the LHT is a very good all around bike.

I'm not saying don't consider the electric, I think it may be the best way to help you get into the shape you want. And when you get there you will always find use for it.
I suffered a spinal injury and bought my first ebike to help me regain my strength. Now I have a stable of bikes but still love my Giant. I ended up adding an XtraCycle kit to it (an extended rear end for large cargo carrying capability) and it makes for a great cargo hauler.

nwmtnbkr

I got the Currie conversion kit, which has most of the same motor components as their ezip and izip RMB bikes, for my 21-speed mountain bike. I retired to the far northern US Rockies and found I wasn't riding my bike much because my knees would ache after riding the hills here. I can't say how much I love this kit and my converted e-bike. The Currie non-hub motor has a good amount of torque. That said, don't expect to be able to hit the throttle and go very far without pedaling. However, if you're willing the pedal, the electric assist will be great to give you some assistance when you're getting tired and help you go farther. I would agree that using electric assist should help you stick with biking and get into better shape. I would disagree that you will outgrow it. I've increased my mileage with electric assist and will continue to increase it next spring and summer once I can start riding the unimproved mountain roads in the forest again. I've gone 25 miles up mountain roads with my e-bke and still had power in the battery when I got home, but I pedal and only hit the throttle for help up the hills (we have very few flat stretches here). There's one mountain road that I want to take to the peak, but the grade of this gravel road is steep enough past the point I've ridden that I know I'll need more battery power because my knees will need assistance. One of my winter projects is to buy ThunderSky LIFEPO4 prismatic battery cells and build my own 24V LIFEPO4 battery pack. One item that I would suggest that you buy is a volt meter/power analyzer to keep track of your battery's power drain. Hobby King has an inexpensive one ($25) that's gotten good reviews. https://www.hobbycity.com/hobbycity/s...power_Analyzer
Good luck.