Frame differences between 700c and 29er? Before you answer: no matter what bike I would change tires to 2" slick front, 2" semi-slick rear, so in other words, tires in this question does not play role (now I have 26" MTB and I use 2.35" to get the desired effect).

I am looking for three things:


max speed on the road in short distance (when you spill out your lungs)
maneuverability in city traffic (going between cars)
and taking long trips on hard surfaces comfortably (and safely)


How the frames of cross 700c bicycle and 29er affect those three factors? 

I already noticed that since 700c have usually flat top tube of the frame falling from the saddle can hurt, 29er has more clearance -- so this a plus for 29er in terms of safety.

I don't consider downhill, going through mud, sand, big rocks, and on the other hand only smooth asphalt.

Update: example of cross 700c bike: http://sklep-romet.pl/index.php?route=product/product&amp;path=61&amp;product_id=64 and 29er as well: http://sklep-romet.pl/index.php?route=product/product&amp;path=59&amp;product_id=85&amp;size=MTB%2029ER
Since both the bikes you link to are mountain bikes, you seem to be primarily concerned with wheel size or frame size. 

But the two wheel sizes are the same = 700c is, more or less, a rim size, while 29" is the outer diameter of the tyre (except that obviously you can get different width "29er" tyres and that affects outside diameter). That confusion is why tyres are now actually sold by ISO rim diameter - specifically the bead seat diameter. If you get that right the tyre will go onto the rim (it may not fit into your frame, or it may be far too fat for the narrow rim, but it will go on).

Frame size matters when you convert one of those to ride fast on sealed roads, you're going to need to do more than just switch the tyres. Most obviously, the 29er is generally lower than the cross frame so when you put the seat and handlebars up to get a better position for fast riding you may find that the 29er can't do that with the stem and seat post that come with it. So you'll probably have to buy a rising stem and possibly a head tube extender, and (less likely) a longer seatpost.

The gearing is also different, 48-11 top gear on the cross bike and 42-11 on the 29er. For both bikes you're probably going to want higher gears, but for the 29er the jump is going to be significant meaning you might need to change the front derailleur as well. I suggest allowing for a 50T or 53T large chainring, which on the cross bike is a small change and may not be worth while. It depends on how fast you ride and pedal.

Both frames are aluminium, just like most mid-range road bikes. I don't think that matters for what you're doing.

On that site the touring bikes (TREKKINGOWE?) would probably be an easier conversion to what you want, but I suspect you might prefer a cyclo-cross bike (drop bars, disk brakes, slightly heavier/stronger than a road bike). Cyclocross bikes are or were made in Poland, but the website for 'Scattante' is gone. Here's a German manufacturer instead :) They won't carry as much weight as a touring bike, but as a result they're lighter. And they're usually designed for more speed.