Since the question is about "sweet spot," there is a cost/benefit analysis involved (all engineers, managers and executives will recognize the concept LOL), therefore there is a personal judgment call, likely in this case linked to personal finances.
Do not get me wrong, I admire the work that Wayne does at American Hunting Rifle, and I will be the first one to say: if you can afford it, get him to work on your CZ. Period. And I love the Blaser system too. Heck I still own one of the Mauser 66 that invented the concept!
This being said, there are a lot of folks who can save slowly and painfully $,1000 to buy a CZ and who cannot afford a $795 AHR upgrade #1, never mind a $1,795 upgrade #2. Sad but true.
One can still own a near perfect DG rifle for the cost of one CZ and a few hours of personal time with the appropriate fine grit sand paper and valve grinding compound. Heck, how do you think the 'smith' smooths your gun LOL?
You will be positively amazed at how slick a standard CZ 550 will become for a grand expenditure of about a few pennies and a few hours. Check specifically:
- how the central edge of the magazine follower plate binds inside the grove for the ejector blade in the under side of the bolt (solved by rounding the central edge of the follower);
- how the burrs of the ejector blade grind inside the ejector grove of the bolt (solved by deburring/polishing the ejector blade);
- how the burrs of the lower rear bridge machining grind against the bolt (solved by deburring/polishing the machining of the lower rear bridge);
- how the forward edge of the extractor collar binds inside the upper rear bridge (solved by rounding the edges of the extractor collar and polishing the inside of the rear bridge);
- how the machining burrs on the inside and lower faces of the feeding lips grind against the feeding cartridges (solved by polishing carefully - but NOT REMOVING MATERIAL from - the feeding lips;
- finally, coat liberally the bolt with valve grinding compound and cycle the bolt one thousand times while watching TV...
Again, you will be amazed at the results...
Regrettably, the CZ does not offer a true safety, i.e. a safety that blocks the firing pin. Instead, they offer a sear blocking safety which cannot prevent the pin from firing the gun should the sear slip for whatever reason (e.g. the gun falling, or a defective trigger "tuning").
This is the one truly needed upgrade to the CZ (and, of course, it is part of the AHR upgrade #1).
Aftermarket firing-pin blocking safeties are widely available for the CZ (Lapour, Gentry, AHR, etc.) and the machining to install one is mostly limited to drilling one small hole in the bolt handle with a carbide bit and fine-tuning the engagement of the camming surfaces, which is a little tricky. If you do not know what I am referring to, do not even attempt it. Get a pro to do it. These are the only $250 you really need to spend.
So, if every $ counts, a $1,000 CZ + $250 firing pin locking safety + 4 hours of your time with sand paper and valve grinding compound will get you, oh, say, 95% of what you get in a $5,000 "custom rifle,"
cosmetics excluded.
As for caliber, my vote is .416 Rigby: flies almost as flat as .375 H&H but hits noticeably harder and can triple-duty nicely on either side of the power band with .375 H&H on one end and .458 Lott on the other end.
So, I will submit to Mr. and Mrs of the Jury that the cost conscious sweet spot is $1,250 with a CZ: 95% of the functions for 25% of the costs.
PS: let's keep in mind that the Rigby of London themselves used ZKK/CZ actions for decades before Mauser recently restarted the production of magnum length actions. If they were good enough for Rigby, I guess they are good enough for me... And CZ barrels pretty dang good too...
If money is not issue, there is a long list of other spots that can be pretty sweet...