Every i1 Pro measurement device is able to create CMYK-Profiles, it is not an issue of hardware, but software. You will create RGB-Profiles when profiling printers driven by regular windows printer drivers, because they work internally with RGB. If profiling for RIP-Softwares, you have to create CMYK-Profiles. With i1 devices comes a software named i1 Profiler, depending of the package (i1 Photo, i1 Publish etc.), it is equipped with CMYK-Profiling or not (an option of the software).
It totally doesn´t matter what the i1 Profiler is equipped with if you use internal profiling capabilities of your RIP-Software. Most of the softwares have that capabilities, some of them by standard, others as an option. Some RIP-Softwares (for example Roland VersaWorks) have no internal profiler, so you have to use a CMYK-i1-Profiler. If using Mimaki Rasterlink for example, there is a separate software available to buy, named Mimaki Profile Master (very expensive for my opinion, but with additional, very interesting features). For Signlab, an option should be available by cadlink.
The i1 Pro 3 Plus is not neccessary if calibrating vinyl. The main feature of the plus is a bigger measurement aperture, this is important if calibrating rough structured media like fabrics. The disadvantage is that you need much bigger swatches than with the regular i1 Pro 2 even if profiling smooth media. There is a spectrophotometer available with the possibility to change aperture size depending on the job to be done, the Barbieri Spectro LFP (a product from italy), but this device is much more expensive than the i1. I use both in business, and I really like the Barbieri (measurement aperture sizes of 2, 6 or 8mm).
Even if creating own profiles, you will not have everytime the perfect match. You will measure some hundred color values to estimate a color gamut of millions of colours, most of them calculated. And even inks and media will set limits in color gamut. Some RIP´s offers functionality to add own measured colours to ICC-Profiles (Flexi), others will let you read tausands of colour values (Onyx Accuboost) and so on, but with solvent inks on vinyl or banner media, the possible color gamut is small. Proof Printers will often have much more color channels (e. G. additional red, orange, violet and so on) to reach the gamut neccessary for proofing. And shortly when trying to proof a print I run into problems just because the customer have set proof paper with a different white to the paper he regularly uses, and is specified to his standards.
But nevertheless, you will have much better colour quality when calibrating every media and every print mode you use by yourself. Inkjet printers needing additional tasks to calibrate, setting ink limits and doing linearisation, but if you will check the profiling workflow of your RIP-Software, you will be guided into that tasks.