There is lots of advice on here about when a friend, family member, neighbor, etc should suggest advice. But I got the feeling that this is more of a fact finding venture to get the OP's ducks in a row when his friend has questions or wants the OP's advise. I personally relay on my friends advice all the time, even if I didn't know I needed it or wanted it. An example: I found myself in a conversation with a very close friend of mine about something I didn't have any interest in at all. How we got onto the subject? I dont even remember. The subject was cryptocurrency, and the year was 2011. He said I should have my mostly idle computers (he is a tech nerd) mining this "Bitcoin" thing instead of helping SETI when they are idle. "SETI wont get you anything. But BTC will get you some money in return." is what he said. I took his advice, and he helped me understand a technology I knew nothing about. I think the price of BTC in 2011 was under $5 per coin. I got excited when I mined my first whole bitcoin, though it didn't mean anything. I had no way to spend it, and really didn't understand it. But I was mining it. I am very grateful that my friend helped me to get with the times, helped me understand crypto, and get me involved. Instead of being blind to something I didn't understand. I am now heavily involved with crypto, and made back all my investments (and then some) years ago.
Moral of my story: dont assume you know the relationship between the OP and his friend, or anyone for that fact. We all gotta learn somewhere, somehow. The information provided might just save his friend some heartache in the future.
The the OP: I suspect your concerns are valid. He probably will need a larger tractor with more capability in the future. I live in a very hilly area with tons of trees. My friend (whom I speak of above) has a smaller 30hp Mahindra open platform. I borrowed it on several occasions (can be seen here, in this old video:
Well Reservoir - Part 1 - The DIG - YouTube). He said I probably wont need a bigger tractor than the one he has. He lives on flat, wheat fields. He took me to the dealership where he bought his tractor, a small dealership that deals with many different brands. The dealer and the the two of us looked at a comparable LS as he no longer sold Mahindra. The tractor seemed nice, and the facts I got from the dealer about the LS brand sold me on it. I started doing my own research and found that a small bump in HP didnt exactly result in a large bump in price. And I know that more HP is always a good thing. I started looking at the XR series, specifically the XR4145 without the cab or without the HST.
I got my ducks in a row financially and went back to the dealer. Told him what I wanted and he gave me a price. He then gave me a price for the XR4145C, the XR4155, and the XR4155C. I was concerned about the cab, worried that the branches from the trees would damage the glass. The dealer told me that he has only replaced one door due to operator being an idiot and leaving the door open while traveling though a gate. Trees simply dont brake the glass, and having heat in the winter, AC in the summer is definitely worth the small bump in price. I decided to go with the XR4145C and was/is not disappointed. I only have one regret, and that is, I should have gotten the 55HP. Not saying the 45hp is a slouch, but having that extra power when going up my steep driveway with loaded tires, a heavy implement, and in Range-4 (road gear), it does lug down the engine.
Some facts:
No one has ever said they needed a weaker tractor. Smaller? maybe. But never weaker.
People are hesitant about a cab, until they have one. Then people who have tractors without cabs are jealous of their friends with them, especially when out plowing snow.
Ballast with hills is a must. Keep that center of gravity low. I've never tipped it, only because I chicken out before it would. But that ballast keeps me planted. Bigger tires = more ballast
Lifting capacity is HUGE! He will use that FEL more than he thinks. And he WILL attempt to lift more than the FEL is rated for
Spacing between trees is a slight concern, but the only time that has effected me is when I slid sideways (in the snow) between two trees front to back. A chainsaw was my only hope. But that has been my only issue
I didnt follow my friends advice on selecting a tractor. But that does not mean that I didnt listen or value his opinion. We have different land with different goals and different financial abilities. He is jealous of my tractor and often borrows mine for larger jobs he has. Be there as a friend, offer advice when he needs it, if he knows it or not.