Sorry, william, but your understanding of digital is very weak.
There are lots of "full frame" sensors. Constant improvement will always be the case for ALL technology. If you get a camera that does what you want, you can easily ignore the constant upgrade process until you want to get back in. The fact another camera has been introduced does nothing to negate the one you already own. There are HUGE advantages to digital beyond simply not having to buy film. The fact you are unaware of them is not a condemnation of digital, nor an argument for the superiority of film. You may have noticed that there are very few photographers, professional and amateur, who have made the switch to digital long ago, and who would never go back to film. Film has become an "artistic choice" that some still make, but I know of almost no one who doesn't think that digital is empowering and liberating for their photography.
For your problem with the balloon photography, my advice is also to think digital as a real solution to the issues you are concerned about. I shot film professionally years ago, so I'm not without perspective, and I know that getting the shots I think you are after is far more likely with a good digital camera system than with film. And shooting at high ISO values (likely necessary for what you want) is many, many times better with modern digital systems than with film. Re-think your "objections" to going digital.