Which one you say is better and why? Is the flotation of M34 and important feature?
Icom M72?
http://www.paddling.net/message/showThread.html?fid=advice&tid=681205
I recently sold my 5 year-old M88 and purchased a M72 after trying my brother’s new M72.
The M72 fits a bit better in my hands and is a little easier to use with gloves on than the M88.
Since I tether my radio to my pfd the floating feature of the M34 wasn’t an incentive.
YMMV
Floating good
I’ve watched a friend miss his PFD pocket and kerplunk his radio into 100 feet of water.
M34
I think the ICOM M34 is a better model - why? - because I got it as a gift (e.g., FREE)!! The flotation feature is nice if you fat finger fumble it - but you should have it tethered to your PFD anyway!! Watching it float away would seem to be more painful than not seeing it as it sunk!!
One reason for a non-floating model though is that they are typically alot smaller which means they go into your PFD pocket easier. (or attached on the outside where it won’t poke you in the eye when you roll)
S
M72 better than either
One issue with the M34 is that in order to reduce the density of the radio, the battery is quite a bit smaller which in turn means the battery life is around half the other radios. The M88 has features, such as the ability to be programmed for LMRS and Ham channels, which are of no use to most paddlers and is one reason the radio is more expensive. It is possible for a radio to be too small in terms of display, buttons, and general “fit in the hand” depending on the user"s hands. To me the M88 is too small, the M34 clunky while the M72 has a nicer form factor than either M34 or M88 along with other advantages. They all provide essentially the same RF performance on the marine channels so it is preferential matter. Not that I own any of these, but I have spent a fair bit of time playing with/evaluating them.
I hate the M72…why???
because I dropped mine off the side of my sailboat…and it sank. Beautiful VHF, best handheld I ever had. Have an M34 now…it floats and I like the big keys. Have the older Ni-cad battery model, and battery life stinks, even when not being used.
M72
But keep it tethered or fixed to a float of some kind.
now ya’ tell me 
NM
I have the M-88
Best one available when I got it. Small, fits in any pfd pocket. LONG battery life. Waterproof without a bag.
Downside? It can turn on unintentionally and drain the battery to zero… this is a costly mistake with LIon batteries… I know from experience.
As a Bonus, they are headquartered in the city I live in so service is a matter of dropping it off on the way home from work
ICOM = GREAT radios…