Make It Mine does need to be removed for Springtomize to work...cant say it any other way. I do use Winterboard and always will...there is absolutely nothing wrong with it. My battery lasts two days easy and I do not have springboard crashes except as was mentioned earlier and I have removed the culprit.
As already stated...Make It Mine does not work anyway and has not for over 4 months. The Dev seems to have stopped managing it so it is a dead app and the only reason I had it installed was for a hopefull update. MIM is broke and dead with iOS 4.2 and higher.
Your fear of Winterboard is no longer valid and you are just torturing yourself over something that works perfectly fine and has for quite some time. Summerboard is no longer needed and most of us have turned it off long ago.
The times and opportunities are passing all of you up that are still stuck down in the pits of 4.0 and 4.1...your loss, I enjoy all the new opportunities and theme options. Kind of like using a rotary dial phone on a party line...time to move to the 21st century