Something to remember about 70cms is that it can be a real 'life-saver' in some instances. I have done a number of activations using a hand-held and J-pole in and around NW England and N. Wales. The population density is such that 2m FM is very successful with simple equipment and as someone who mainly does HF activations, it's a pleasure to be able to active with simple equipment.
However, interference from co-sited or nearby PMR equipment can severely impact success. Some 2m handhelds are much better than others. My preference is for a Yaesu VX-170 (or later FT-270) for 2m as it is much better in such conditions than other handhelds I have. My Icom ID-80, Alinco DJ-G7, Yaesu VX1 all suffer badly from breakthrough and overload on 2m when used with a bigger antenna than the rubber duck and the ID-80 can be unusable even with just that. Similarly an FT-817 on 2m is very tolerant of such conditions.
In these circumstances, switching to 70cms has been key to successful activating. On Grayrigg Forest LD-037, my ID-80 was being badly overloaded from the commercial tower sites further down the hill. I was having huge difficulty hearing any signal that wasn't S9 on 2m. Switching to 70cms saved the day as I worked plenty of stations with no interference. This is something to always bear in mind.
As for 70cms as a primary band to use is a choice for the activator. Gerald G4OIG showed a small beam & PA made 70cms SSB quite viable but that does require a key band of chasers. Vicki M6BWA has shown and still shows that 70cms from a handheld with a set top antenna is quite viable. What they will both tell you is that the problem is not the paths that can be worked but getting people listening on the band in question.
The recent VK-EU and EU-NA events have shown to people that if you want VK-EU S2S contacts, getting a big bunch of people on the air at the same time is key. A 70cms activity event would let people see how well it works for SOTA certainly in countries in Europe that have a high population density. People in parts of VK or USA might find 70cms a little lonely!
It just needs someone to suggest a date and time period for a 70cms activity session to demonstrate the band's potential to people who have never used it or only used to access a local repeater etc. The last time we had a UHF event in Scotland I worked 5 S2S contacts on 70cms which put quite a big smile on my face as the band is quiet up here outside of contests etc.