I had a friend send me load data for Solo 1000 for .44 mag & .44 special. It is clean burning and I use it all the time.
I have been shooting low powered hand loads with 240 gr lead round nose bullet for 20 years with great success in the 4 inch 629. When I load factory rounds or the high power ammo I hardly notice the differance until about the 12th shot. The point here is, I only load up the heavy stuff when out in the field or when it is needed. I mostly shoot this gun recreationally, as I suspect most people do on this forum.

The advice I can give you to offer to your friend is get one, what ever you can afford. I like the standard 4 inch w/o the full lug.

I have hand loaded every combination I could brew up for this gun and find at 25 meters it is all mostly the same. I put a scope on it for a while just to see how accurate this gun could be. Shot from a rest, shot from sitting, standing and every other ways I could think of. I switched to open sights and also tried a red-dot on this fine revolver. So, I went from the lowest load to settle on 7 gr Solo 1000 behind a 240 gr lead round nose bullet just because I have fine 7 grain pellets next to my bench. It is an easy reference for me. ( my favorite light load is 4.2 gr of solo behind the 240 gr LRN)

I started my boy on a daisy 717 which is about the same weight as the 4 inch 629. I have let my newbie nephews shoot the loaded down .44 ( and also my .45) with great results. It is just a blast to shoot and exciting to expose younger or inexperienced shooters to shooting the big bores. ( There ae braggin' rights to be had: "I shot a .44 magnum and it was way cool". We shoot paper, but rolling around a big coffee can is just plain fun. They mavel at the big raggedy holes in the cans and want to take it home as a trophy. I think I have turned more new shooters on to shooting by letting them shoot a real S&W .44 than any other gun. I was a 4H youth shooting instructor for a few years and about every kiddo and parent who got to shoot this gun remembers the experience.

I love this gun and so will your friend. Get him into reloading and he will save a ton of money on ammo, and be able to load the rounds to low recoil ammo ( we affectionately call powder-puff loads ) When starting out we don't talk too much about how un-manly these loads are. We just go and shoot and have fun. I only pull out the full power ammo when I wish or need to refamiliarize myself with the heavy rounds in this gun. But from the years of shooting this gun I have no hesitation or flinch when shooting the high power ammo because of so much practice with the powder-puff rounds. Both loads will knock down plates and both have about the same impact point at 25 meters. ( close enough to knock down a plate MHO that is as practical accuracy as it gets; for practical defensive shooting)

So good luck with your friend's choices but one last comment. He or any man will be proud to own a S&W 629 and will likely never regret the purchase. Especially if he learns to reload, saving money, shooting low recoil ammo and adding a whole new dimention to his shooting hobby.