I was just handling that very JLC reverso last week at a boutique and I must say it is quite impressive (coming from an IWC fan here and I own that very 8 days Portofino too).
I agree with Godzillaz that these are 2 very different watches and you are really comparing durian and rambutan here. One of the reason I went for the Port 8 days was because I never have the liking for rectangular-like watch case, and that's really it. You really need to try it on an let us know what you feel about them.
Anyway, here's my bias opinion: Go for the IWC Portofino 8 days, it makes a better statement, unique, and carries much more character, great for formal and casual wear, durable and very stable movement, makes head turn everytime. It may not be as 'fine' as the JLC reverso and cannot match the quality pedigree of movement, but heck, it makes a louder statement and has lot more fun-factor IMO. It's a good balance of a not too bad manufacturer movement and great visual impression and aesthetic. Just my dua sen...