Both are very capable radios. The FT-65 is lighter, smaller, cheaper, and of course you can buy it new.
My personal preference for use on a SOTA expedition would be the FT-60. I prefer the larger keypad (especially when using with gloves), and I much prefer being able to change channels with the knob on top of the radio, rather than the up/down button on the FT-65. I also prefer the audio that comes out of the speaker of the FT-60. Although heavier, I really like how it feels in my hands.
All small points of course, and as I said, the FT-65 is a perfectly usable radio for SOTA.
I may be biased as the FT-60 was the first proper handheld I bought when getting into amateur radio, and I also used to qualify my first SOTA activation. Sadly it is now residing somewhere on Mynydd Uchaf, GW/SW-031 I have since managed to source a replacement though.
IIRC the FT-65 is a “radio on a chip” design like the Chinese radios, where the FT-60 has a proper discrete component receiver. Does it matter? Maybe not, but it is a material difference.
I really should pick one up while they’re still available NIB. I don’t need one, but it would make a good spare to my Kenwood D74. The FT-60 has a better receiver than the D74 and I don’t really use the D74 to its fullest capacity.
The receive performance of the Icom ID-52 appears to be on par with the Yaesu FT-60 and VX-170.
• Third-order dynamic range (wide, 2m): 85 dB
• Third-order dynamic range (narrow, 2m): 73 dB
I’m surprised that you found the FT1500m a bad rig and bad RX as the one I have is certified Billinge Proof (G/SP-017) - one of the more notorious summits for breakthrough and desense.
In all seriousness, I have an FT-4X handie that has performed quite well (not perfect). Advantages are that they are available new for about £60, they are very simple to operate and have a little extra filtering over the Boafeng style handies which definately makes a difference.
Mine has been with me on hundreds and hundreds of activations. It’s good with pager breakthrough… but not totally immune. I do still carry a SOTABeams filter and it does make a difference in some cases.
The waterproofness has been tested very severely… so far it’s still working!
I’m not saying water resistance isn’t valuable, just that IP67’s requirement of total submersion in 1 meter of water for 30 minutes isn’t necessary, even when operating in the rain. My D74 is IP55 rated (dust protected and can withstand water jets) and I’ve stood in the rain many times working contacts with that radio. Requiring that rules out a lot of good radios that are water-resistant enough for anything short of swimming.
I’ve tested two of the ‘cheap Chinese’ radios versus a Japanse design (but made in China), and the results speak for themselves. Video link below:
(trying to figure out how to make it work - it’ll be here shortly)
I’ve had very good success with mine, and it features in the video link above. Very pleased I bought it.
The two I have ( one inherited) are awful mobile as as every shop,petrol station and factory you drive past causes the RX to break the squelch ( no matter the setting) and cause a horrible racket and if you are near any RF transmitters the thing just get overloaded. In the end I swapped it out for a Maxon Commercial radio which never makes a noise unless there is a real signal on that frequency. The problem is it only has four channels which I have programmed for local repeater use. If I can find another I may go this way but program it with simplex channels. The Two FT1500m are that bad that I have been tempted to bin them many times !
I never use mine in memory mode anyways, always vfo mode, mainly because I rarely use repeaters. I also didn’t really use it mobile (just as a passenger - see below) so not a problem I’ve encountered.
The only issue I had with mine was a small fire in the car as I turned up the power and melted the cable to the cigarette lighter thingy.
It rarely sees the light of day now too as I obtained an FT-8900 quad band that I really do like and has duplex for satellite stuff.
I have since managed to source a replacement though. 
