Sonar 7

I was still happily using Sonar 7 until early last year, but after testing out the 30-day trial version of X2 I succumbed and upgraded. The newer versions take a bit of getting used to but there are some good features that become hard to live without after you start relying on them.
 
If you want to know whether drum maps are now any easier to use, the answer is no.
 
Existing plugs should work ok.

I also suggest you download the free demo of X3 and give it a whirl for 30 days.
 
I don't happen to use Drum Maps or the Piano Roll View, but it was my understanding that folks are able to use the two of those together for creating drum tracks.  (I happen to still use Step Sequencer for creating drum tracks, and I just use the note names and note numbers of the various drum kit pieces I have set up).
 
There was a GIANT and complete redesign of the Sonar user interface that began with Sonar X1, and has continued to see modifications through the current Sonar X3.  It IS quite different from Sonar 7, but once you get used to where things have been moved and are accessed differently, you will most likely come to find it quite a bit easier on the brain to get things done.
 
It is also VERY stable - if you move from a 32-bit environment to a 64-bit environment, you may have some fallout on some 3rd-party plugins, having to do with bridging software that makes it possible for 32-bit plugins to run in 64-bit Sonar, but aside from a potential for some of that, things should work extremely well for you.  (Sonar comes with something called BitBridge for automatically trying to make 32-bit plugins work in 64-bit Sonar, and if that doesn't work for some plugins, you could try a 3rd-party utility called JBridge, that some find helps those plugins work - I think it is about $20 for that, if needed)
 
Bob Bone
 

I was running SONAR 6 PE since it came out up until a year ago …
I still dig it and I still use it sometimes ...it is comfortable and I know my way around it ….
I got ahold of X3 PE last year and I was like what the hell ….
it felt like I went from driving a mid 70's Chevy Nova to strapping myself into The Nasa Space Shuttle ….
as far as my personal experience go's ,
I'm very happy with X3 …it has been a challenge to readjust to a different workflow than what I was used to...
once I started cresting the learning curve …I saw the light incrementally …
things started getting much clearer and easier for me ...
good luck OP, 
Kenny

Yes, the step sequencer was introduced in SONAR 7, IIRC, and underwent significant improvements in 8.5.
 
The option to invoke the step sequencer isn't enabled until you select a MIDI track. That may be why you're not seeing it.

Never mind, found it!