I haven't used either of those planers but did research before buying.
The consensus was 'get the Dewalt DW735X'.

Looks like the Dewalt is similar in price (retail) to the Rikon.
I picked my DW735X up on sale for $450. And I got the stand for $100 from Amazon. This was November, I think. So I'm sure that helps with pricing.
Anyway, I've used the planer on a bunch of walnut and hard maple and it works really well. Super easy to setup and use and has no trouble making the chips fly. [big grin]
It is definitely NOISY. By far the loudest tool I have. Though, my Mini Gorilla is a pretty close second.
I've read that if you upgrade to helical it quiets the planer down. But really, with earplugs or muffs on it doesn't matter a whole lot.
The Dewalt is rated at 13". I had to shave a slab table top down to 12 7/8 or so to fit. I haven't taxed it on the max height yet.
It doesn't have helical but it cuts extremely well and the blades are super cheap and very easy to replace. The 'X' version comes with an extra set of blades.
Also, there were some slightly older reviews that mentioned sniping. I haven't experienced that so far and I'm guessing it's because of the included infeed and outfeed tables. They were an extra cost item before and I bet a lot of people ran without the tables.