Lakemaster Map Questions

Before you suggest a search....I have. I have been on Humminbird's site and it is pitiful at showing the differences....even tried to compare them...NO LUCK

What do the different versions mean?

I see Lakemaster Plus V1, V2, V3, and V4....Is 4 the latest and greatest? Is there a 5?

Does V4 include everything in V1, V2, V3 etc?

In your opinion is the PLUS worth the extra money?

Is Smartstrike worth he money?

heres my humble opinion..I use mine at Fork, I fish there 99% of the time.
I had 2 V2's, I bought a new V4, it was the most current 2 months ago,
I was going to use the V4 on the console cause it was all new. Went to a few spots and
things that were on the V2 were missing, like a roadbed, and a couple of creeks...I was
pizzed. I swaped the V4 to the bow and put my old V2 back on the console...
I see very little difference that means anything,...cept what they left off..