In terms of power it seems to me that Silverados and 1521s have about the same power. I have a Silverado I will be selling in about a week that has about as much power as you can get. Really, power can change from machine to machine depending on motor wear and other factors.
The model 1453 you have should have plenty of power if it has a orignal motor and is working properly. I have seen some dealers install motors wrong and the vacuum has very little suction and that could be your problem. By the way, what color is it? I liked the white ones and it's been a while since I have seen a good one.
Now, about that 2100. First, your hose is shot. You can get a replacement for it for about $35.00 on ebay. After that it should be as good as new. Second, the PN7 can be loads of fun. With a good brush roll in them they can be great carpet cleaners. Third, the metal and plastic body motors are usualy the same depending on when it was made. If the motor sounds good now, and you take good care of it(change bags often), then it should stay that way and I woulden't worry about it. The motors tend to give you plenty of warning before they let go.
Below is a picture of a motor from a Marquise.
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