part of this hobby for me is the building/repairing planes you ought to give it a try.
it will give you invaluable expierence plus the dammage on your plane is pretty minor at one point my NEXTAR looked like a half peeled banana and after repairing it I flew it for quite a while after.
the servos that come with the NEXTAR as I remember are Futaba 3003 servos there OK but not ball bering the 3004 is a bit of a step above in Quality I ended up selling mine when I retired my NEXTAR.
as for the S.K.senior your not really going to advance with it more like a sideways move they fly great and are a docile plane but its not going to help you learn to fly the twist any more than the NEXTAR.
this is the progression my NEXTAR has taken.
repaired with red monocoat,the only covering I had handy at the time,hanging on the rack by the T.V.
stripped of covering after some more tune up repairs and mods fitted with its new OS 61fx.
finished with floats and a new life after collecting dust in the corner for a couple of years without radio or engine.
you could also turn it into a tail dragger several have on RCU its also a pretty cool conversion.
and a shot of my new gear location if i decide to go back to land flying I will turn mine into a tail dragger also.