Anyone?

I can't say definitively whether solo mining with a single average cpu will or won't work but I can point out some things for you to consider.

First, define average cpu - there are huge differences in processing power depending on cpu type and how many cores.  A rough guess on a current cpu is 12 Kh/s per core/thread.

Current Network hash rate 72 Mh/s  (30Mh/s - 100Mh/s)
Average personal cpu hashrate will be about 50 - 70 Kh/s (4 - 6 cores).

Do the math and decide, it's a long shot but I suppose you could get lucky.  But I doubt you will get lucky often enough to keep up with earnings from a pool.

Example:
My own mining on a pool with about 100 Kh/s  earns about 8 XMG per day - but this varies a lot depending on difficulty and luck.  Sometimes even on a pool it's as low as 1 xmg and as high as 15 xmg in a day.
Hope that helps you decide.

 i'm using https://xmg.maxminers.net, working fine and i seem to be getting my fair share   (14 in the last 24h w/6 cores pumping...)

The interest rate of the POS II is difficult to calculate because of the way it works with Magi, there are several things that affect it such as difficulty, amount of coins, age of coins, etc.  I can't give you exact numbers but the percents I have seen are between 1% - 4% annually with an average of 2% usually - that's been the case in my wallet.  This is quite low compared to many other coins and that is why the POI campaign is such a nice bonus.

The POI campaign is beneficial because it's a larger return in a shorter amount of time, similar to how we used to get interest on savings accounts, (the good ole days), but at the same time, you are also getting your own POS in your wallet, so in essence, you are getting two for the price of one just for holding the coins.  It's a good opportunity for beginners to get into crypto and learn how it all works while earning more coins in the process.  Hope that helps.