dodgyknees.......still laughing after reading your post! You're absolutely right about a few things (especially relating to me!). 'Older bloke'....definitely! Also correct that fixed mags were what I started with. I do use variables on my rifles, though, (particularly in Africa) on a Blaser with 7mm Rem Mag barrel and a 375 H&H barrel.
I think your comment that the .243 Win requires precision to be a bankable killer is extremely well made. I have seen some of the shots made (particularly in NZ) and also here in the UK on big reds and there's no doubt that absolute accuracy is required with a 100g bullet. I feel exactly the same about my own 25-06 with 100g, hence my self imposed 200m limit on live game, despite knowing I can plonk them into a target out to 250m and further.
Your comment (and Sako75Hunter) about starting at low mag, then increasing the mag for the shot is also very true, particularly when you've spied the beast from distance and time is on your side.
As a white haired engineer, instead of 'giving you a serve', I offer you the engineer's favourite guideline - the KISS principal.
Keep It Simple, Stupid! Some of the best engineering you will find is simple, robust and just works. That's the beauty of the fixed mag scope - not a lot to go wrong mechanically, and not much for the man behind the rifle to screw up!
One last trip back to the cost issue (white hair, and Scottish

).....I'm guessing that JORD4N might be starting out and cost might be a consideration (if I'm wrong, then apologies!). A good quality fixed mag will give him many years of excellent service, and if he then wants to change, that's his choice.
Great thread guys. JORD4N - good luck with your scope, and enjoy your rifle.
S.