I'm obviously extremely biased, but here is some logic to consider, and you can make up your own mind.
If winning big races and points series around the country and world = struggling, then maybe we need a redefinition of that word?
Honestly I beleive there is a significant difference between the two, but neither is "the perfect car for everyone".
If you're a casual weekend warrior who has a desire to just finish your races, and don't have the drive and competitive motivation to advance to your skills to the utmost level possible, the TC5 is most likely the best choice for you.
If you desire to push yourself and your car to the absolute limits of ability over time to become one of the best in the world, then I'd recomend the Mi3.
Another thing I'd recomend for you - talk to AE and Schumacher sponsored drivers at your track/in your area. Sponsored guys are there to help everyone, and also provide specific support/setup help for other drivers using their brand of product. You should be able to count on them for help on and off the track, so the simplest way to choose is to talk to each, and decide which team treats you with respect and is interested in helping you out with your car.
If you don't have anyone in your area, check out the Schumacher Corner thread here and see what we're made of. We have fun, we rib each other a bit, but ultimately we're here to support and help YOU get the most from your car. No attitudes, no BS, just a bunch of guys like you who like to race cars and are interested in growing the sport.
Regardless of what you choose, just remember to have fun racing and help the guy next to you - because without him, you might be racing alone next week.