There is a big step from Analog 480p30 to Digital 720p30 -- specially for technical slides which are full of text.
The step up from 720p30 to 1080p30 *is* better, however it is nowhere near the same perceptual quality increase of the previous step and it increases the bandwidth and processing power required significantly.
The step up from 1080p60 to 4k30 is unnoticeable for our presenting use case and the resources requirements are huge. We are much better investing in improving the audio quality.
FYI The Opsis could be used at 1080p30 if your projector supports that (It doesn't however support 1080p60 on the HDMI ports without a lot of hacks which I have not had the time to do).
Tim 'mithro' Ansell