This almost feels like the never ending topic lol which I don't mind. The question is 

I have most my spinnerbaits with 4.5 than 4 as the back

but recently starting getting some with 4 front and then 3.5 in the back

 

Now befits to this is maybe smaller baitfish BUT doesn't a spinner thrive for the vibration which the larger blades would give anyways is there really a point to get the 4 front with the 3.5 back, is there a situation I'm missing?

These are 3/8oz spinnerbaits 

 

Advantages of using smaller blades are simply more speed/deeper retrieve/more stablility which I’m sure you already know. And another advantage is that they present a smaller profile for the bass which sometimes they like as you mentioned. 

Burning a spinnerbait can be effective for smallmouth, works better with small blades.

 

I’ll talk about my preferences first. I can’t speak to double willows since I don’t use them enough but for either a colorado/willow or indiana/willow, I generally prefer a pretty small colorado or Indiana on my smaller weight spinnerbaits… let’s say a #3 or 3.5 at the largest. But my willow I like to be large. Either a 4.5 or 5 depending on the weight. Otherwise, for double Indiana, double colorados, or single colorados which pretty much encompasses the rest of what I throw, I lean towards slightly smaller or average size blades.
 

Why do I prefer these size combinations? Because I’ve found these to be versatile and effective for me. I want to be able to take a spinnerbait and run it in 3’ of water near the top, and then turn right around and also be able to crawl it on the bottom in 12’. 
 

I like other blade sizes and combinations but eventually everybody finds what works for them and that’s kinda what works for me. 

 

By the way, I totally agree. These spinnerbait blade threads continually pop up and seemingly in clusters at a time. I’m not complaining either. They make for fun discussion. 

Blade sizes are not the same  with different manufacturers . I use a fairly small willow 4.5 from Janns on 1/2 oz spinnerbaits a lot .I rarely use a lighter spinnerbait . SpinnerBaits dont need a lot of vibration to get a basses attention, even in dirty water . 

15 minutes ago, scaleface said:

Blade sizes are not the same  with different manufacturers . I use a fairly small willow 4.5 from Janns on 1/2 oz spinnerbaits a lot .I rarely use a lighter spinnerbait . SpinnerBaits dont need a lot of vibration to get a basses attention, even in dirty water . 

Thanks for mentioning that. My post references hildebrandt blade sizes since that is what I am comfortable with.

 

And I agree with ya that a spinnerbait with small blades still commands a good amount of attention. It’s a pretty aggressive bait in my mind, even the smaller frame ones