I approve this question. Many might not think about cross-shopping a 25 year old car with a 10 year old car, but I personally have struggled with very similar debates. I just went from a $30k supercharged SRT8 Jeep to a GVR4 for the very reason you are considering. The Galant will never compare with the amenities of the Jeep, but comfort is relative. Did all that extra stuff, because it was newer, make me any more comfortable? I would say no. My Galant is very comfortable to drive every day and the a/c, although not automatic, keeps me cool just fine. I will probably do mods to make my Galant less comfortable for the sake of handling anyway.
As yourself and others have mentioned money seems to be the biggest deciding factor when it comes to my toys because it is compounding. A newer vehicle is more expensive, as is the insurance, as are the parts. It was going to cost $12k for a built engine in my Jeep. I have seen plenty of built shortblocks for 1G DSMs for around $2k. Although if a vehicle is too old, or too rare you can also struggle with parts costs and availability. Unfortunately the Galant is getting old enough now that parts availability is becoming a struggle. Fortunately drivetrain parts are still readily available due to the the relation to the DSM cars. Then there is the concern from driving a nicer vehicle more often and getting road damage and door dings. That's why I finally sold my GT500. I was so afraid of it setting in a parking lot somewhere and getting hit, or keyed, banged with a car door or grocery cart. It just sat in the garage 99% of the time. With all that being said I do look longingly at times on an Evo for a few reasons. With a newer vehicle it is easier to track the history, and potentially get a vehicle that has been exposed to less rust causing conditions and hacking by less caring owners. Also there are definitely advantages to the improved technology during the 15 year difference.
If you already have an Evo it is "the devil you know". You already know the issues and little quirks. With a GVR4 it can take you months to figure out what has been hacked or broken and then repaired, maybe or maybe not to your standards. You could struggle with gremlins from old hardened wires and hoses for a while.
My recommendation would be to keep what you have and be patient. If you're worried about the payment, it will be gone soon enough. In the end you will have a newer platform with better technology, and parts will be more readily available for longer.
