Thank you all for the replies, which are all very helpful.
The fields will not all be done at the same time due to rotational grazing, so the size of the acreage should (hopefully) be fine for us to deal with in smaller bites. The main (frequent) use will be on a 4 acre/2 acre paddocks, the remainder of the pasture will be harrowed less frequently.
I was worried about the spacing of the tines too, but their closely spaced version (the super harrow) is way OTT for what we need with the electric raise/lower etc. The tines are all genuine Einbock, so they should be decent quality, unlike others on eBay etc and Logic are a reputable brand so I hope it should be very well made.
The local supplier is offered to demonstrate the harrow on our fields, so based on Maggy's experiences we seem to have little to lose by having a demo.
Thanks again.