Matching isn't just based on impedance, it's primarily based in driver characteristics. Material, resonant frequencies, tone, etc. That's why it's much easier to use speakers made by the same manufacturer because they're bound to have the same timbre, especially if all the speakers in your system use the same drivers.
I was not worried about the Wharfes, I was worried about you JVCs, I knew your Wharfes can take it, but I'm not so sure about your JVCs, Sakuras usually have higher power ratings for the fronts so if it's going to burn any of your speakers, they're bound to be the fronts, and sa pagkakaalam ko kasi, most of the bass is driven to the fronts.
I think those ratings are RMS, and don't worry about the rating kasi most of the time, way lower naman dyan ang kelangan ng speakers to be driven e. No problem with Wharfedales, bro, they're gonna do just great for you. I'm just suggesting that it would be better if you also used Wharfedales for your fronts. The DTX 9.5 system is also great, mas mura pa.
It is also hard to base loudness sa power rating, it's more on the SPL. But let's not get into that.
Regarding impedance, it is more ideal to have the amp impedance be lower or at least equal to the speaker impedance, e.g. : Amp 6 Ohms, speaker 8 Ohms, than the other way around. The latter would cause the amp to operate at a higher temperature, but that doesn't mean na di nya kaya. Pretend those amps are water pipes and speakers are faucets. The lower the impedance, the bigger the pipe or faucet. So if your amp is like 6 Ohms and your speaker is like 8 Ohms, malakas ang flow ng tubig, right? but if it's the other way around, it's like fitting a bigger faucet than your water line, dadaloy pa rin ang tubig, but di na ganun kalakas ang pressure. Hope that enlightens you.