For starters...ditch ATK. It is causing you more problems than helping you and you don't even realize it. Unused RAM is wasted RAM...and trust me you aren't going to run out because Android knows when it needs to dump apps and when it doesn't.
The lowest amount of available RAM my Inspire will drop to is right around 100-120 MB...no matter what apps I run..and thats because the OS knows what its doing and how to do it for the most part.
So don't get bent out of shape over available RAM..and let the phone do its job.
And secondly...the Inspire has WAY more than enough horsepower to operate 2.3 (gingerbread) smoothly. With the popularity of this phone and others like it (i.e. Desire HD, Thunderbolt, etc...), it will have a good life for at least the next 1-2 years.