The Choppa Question

A few months ago I created 2 weapons specifically for the ork warband list. It seem maybe my group will accept it as a house rule. The 2 Weapons are the:

Choppa: The peak of orc craftsmanship. A multi-purpose killing device.
Range: close combat Strength: As user Price: common 5 gc or teef (only Greenskinz can use/buy it)
Special rule:
Multi-purpose: If the warrior score a critical hit he can choose which critical table he will use (bladed, blunt, thrust, unarmed, or flexible weapon)

Big Choppa: The bigger and meaner version of the choppa
Range: close combat Strength: As user +2 Price: Rare 8 30 gc or teef (only Greenskinz can use/buy it)
Special rule:
Multi-purpose: If the model score a critical hit the player can choose which critical table he will use (bladed, blunt, thrust, unarmed, or flexible weapon)
Two-handed: A model armed with a big choppa may not use a shield, buckler or additional weapon in close combat. It gets an additional +1 armour save bonus against ranged attacks if it carries a shield.
Strike Last: A big choppa are so heavy that the model using one always strikes last,even when charging. (Strongman skill helps to overcome this drawback)

What do you think about it?

Eh, nothing really wrong with them, but I'd definitely never buy one; the big choppa doesn't give enough to justify the price tag and rare roll(s), and I'd always want either an axe or a club over a normal choppa.

You could make the Choppa like WHFB rules, which gives +1S in the first round of combat, as well...?

It would be an "orc" version of morningstars and flails (which are 15gc either one), but with the addition of the variant crits.
Something like 18gc for cost, Common for rarity? "Orcs only" of course.

Then you can model all sorts of spiky weird weapons on the model, to your heart's content

Its always nice to have more choppa options, but I am not sure that being able to pick the crit table is that big a draw...

Not really that big but cool. also certain players fear specific critical affects. (me the anoying ricochet)