A little more info will help give informed advice. I personally haven't used either cleaver listed (though I have used Sugimoto's CM steel and use a Sugimoto #6)
Taking the post at face value, I'd say go for the Sugimoto purely from the edge retention point of view. I think you'll be hard pressed to find a carbon cleaver with good edge retention without breaching the $300+ mark, even then I can only think of Moritaka and Takeda for Aogami Super (possibly Mizuno).
Personally though, I would go for the Suien out of those two. As much as I love Sugimoto, I would prefer the full size of the Suien over the Sugimoto #30 and would gladly tolerate lesser edge retention for the larger blade. Of course, this is speculation as I've never used the Suien; it could very well have better edge retention than the Sugimoto, but with my experience, I doubt it.
To probe a bit deeper; is the cleaver for home use or professional? What carcasses are you breaking down? What size knife do you currently use or would feel comfortable using?
For home use, the size of the Sugimoto wouldn't be a problem IMO, if you're prepping sh*tloads, you may well find the extra size/weight on the suien to be advantageous. If it's just chicken carcasses and you're disjointing them, either will do, if you're going through bones of using it for fish or pretty much any other protein I wouldn't use either, I for filleting, trimming, slicing etc, sure, but I would just buy a crappy $15 cleaver from the closest Asian super market in addition for that. If you use a larger knife (240 +) again, I'd suggest the Suien. I found that full size cleavers felt a little clumsy and fatiguing at first, but you pick it up quickly. I tried a CCK 1303 at first (20cm x 9cm) before trying the Sugimoto #6 (22cm x 11cm and about 200g heavier) took me about a month to get use to it, but I wouldn't consider anything smaller now. Since then my sugimoto has been ground down to about 10cm in height and it feels so light (Around 390g last time I weighed it) and it's no where near as pleasant as it was to use at first...still my favorite knife though.
Hope this helps a little. With any luck someone with first hand experience will chime in or the cleaver gurus Jaybett and Andy will make an appearance
Cheers,
Josh