Your friend might think he wants an overstable putter but it won't necessarily help his game. It is the rare player who will benefit from, or even be able to control, an overstable putter. Putting is about precision and hitting fine lines. It is generally easier to control a disc which goes straight than one which turns hard.
If your friend was an experienced Pro with a very strong wrist, then he can adapt to most anything. But then he would already know what disc he wanted and this question wouldn't come up. For the rest of us, we need a putter which can be manipulated to bend in either direction (hyzer or anhyzer) or go straight. Even among very experienced players notice how many of them use a broken-in putter instead of a fresh one.
The disc is actually for me.. The reason i'm wanting a putter that has more hyzer is souly for approach shots that demand a good hyzer at least in the end of its flight. I have a discmania maniac putter which holds a super straight line and hardly hyzers at the end of flight. benefitual in many situations. I'm still experimenting on discs so, i'm def not a pro to say the least. Btw i watched your videos on youtube, thanks for the putting tips on confidence. I need to start that workshop to get my putting "lined up".
For most short approach shots you won't need a hugely overstable putter, even to make them bend pretty hard at the end. I use a Magnet for that shot unless there is a very strong headwind or I need it to skip hard, in which case I might switch to a driver. Most times you don't want to throw a driver on a 100 foot shot but putters and even Mids won't skip like a driver.
A Magnet, when fresh, is pretty strong but still controllable without throwing it hard. There are much more overstable putters out there and some players use overstable putters effectively but I seldom need (or want) a meathook to do the job. Just a notch up in stability from the Magnet is a Challenger or a Focus. A couple notches up is a Banger GT. The rumor is that companies other than Discraft also make different styles of putters but I don't know much about their more current runs. :)
I do like the driver option. I was just searching for an alternative "disc" for those long appoarch and drives that are on a short hole with dog leg left or right. Maybe im just thinking about it all wrong... Thanks for the feedback.
I'm using my firebird more and more for short little (say 80-150') bending shots around trees and bushes. If there is a low ceiling, this is the way to go because even if you miss low a bit, it's still going to bounce up where you wanted it. You won't get that from a mid or putter. If you miss low with those, they'll hit the brakes. If the ceiling is no issue, I still like to bend the putter or mid around obstacles, but try out this little trick.
I diverge from Mark a bit in pitching the Discraft ESP Zone to you. It is an awesome slower overstable mid (though they call it a putter). I call it my short firebird. Whenever there is a shot where I'd normally throw the firebird up and over knife hyzer or around something, but it's in an akwardly short range for the fb, I'll pull this one out. If there's a right to left wind (I throw RHBH) and I'd typically throw a firebird, then I'll pull out the Zone and throw it the exact same and the slower speed compensates for the additional lift and distance from that crosswind. I'm surprised Mr. Ellis doesn't throw one of these as he likes flat discs as a forehand thrower and the Zone is as flat as they come.
Last thing to note, less stable discs will travel further left or right if given hyzer because they hold that line longer rather than diving off at the end like an overstable disc so it really depends on the distance of bend you need and the height you have to work with.
I will vouch for the Vibram V.P. being one the beefiest putters I've thrown. As for understable putters.. . I had a 169 dx aviar that was just buttery smooth... too bad I threw it into a pond. I miss it greatly. :(