Look into the base model Simplicity Freedom.

First of all, if you like what you are using now, try to solve the problem before purchasing a new vacuum cleaner.

The Hoover WT will clean thick carpeting very well. There are a few things that could be happening. First, the rug that you put down may have a plastic backing. This would seal the rug. When your vacuum runs over this rug, there is no where for the air to pull through the rug. The Hoover then becomes "stuck" to the rug. The same would happen if you put down a rug on a flat floor without a pad. You said that you put these rugs over your wall to wall, so the WTW would act as padding. Does your Hoover have the same sealing issue when you vacuum the WTW? It most likely does not.

Also, since you are smelling rubber, your belt is slipping. When was the last time you changed the belt? Put on a fresh genuine belt, then lower the height of the vacuum just enough to hear a change in air movement and vibration from the brushroll.

I can recommend some vacuum cleaners, but I would rather wait until you have tried what I suggested first.