I think both are very nice amps. I have the VTL 450s and a good friend has the VT200 (not the MkII I believe). I like my VTLs very much. They make my music sounds fabulous. The highest complement I can pay them is that while I have envisaged upgrades to various parts of my system (even the rack) from time to time, I have not once thought of upgrading the amps.
As to your questions...
1) Reliability: I have had my VTL MB 450 Signature monblocks for 14mos (bought used at the time) and they have had no problems whatsoever (knock on wood). I have not heard any dealers complaining about VTLs, even if they have competing products to sell (such as Jadis). Reliability seems to have been a bugbear for some in the past (see the archives here or over at audioasylum. It is probably worth asking your VTL dealer about this as well.
2) Weight: they are heavy - 35kg/80lbs apiece - and the weight is somewhat awkwardly placed within the chassis. They are not for people who like moving stuff around every week.
3) Heat: they put out some heat but it's not overbearing.
Notes on #2 and #3: The VT200 is heavy (I'd put it at ~50kg/120lb give or take) and puts out quite a bit of heat.
I agree with Mejames in that when/if you demo the VTL 450s, it is imperative to demo them in triode. While tetrode is very, very good, triode can be magic. I find the VT200 sounds somewhat "hard" when compared to the 450s in triode mode. If you don't need the 400-500 watts that the VTL 450s can provide in tetrode, you might also try the MB 250s, which offer 200WPC in triode only.
Another high-power tube amp you might consider in the same price range would be the Wolcott Presence 220 monoblocks (though I've never heard the Wolcotts, whenever I see comments about comparisons between the VTLs and the Wolcotts, the VTLs always seem to come out second best). I would also recommend trying the Counterpoint Natural Progression series (even though they are less tube amps than hybrid amps). I was very impressed with the monoblocks.
As to your questions...
1) Reliability: I have had my VTL MB 450 Signature monblocks for 14mos (bought used at the time) and they have had no problems whatsoever (knock on wood). I have not heard any dealers complaining about VTLs, even if they have competing products to sell (such as Jadis). Reliability seems to have been a bugbear for some in the past (see the archives here or over at audioasylum. It is probably worth asking your VTL dealer about this as well.
2) Weight: they are heavy - 35kg/80lbs apiece - and the weight is somewhat awkwardly placed within the chassis. They are not for people who like moving stuff around every week.
3) Heat: they put out some heat but it's not overbearing.
Notes on #2 and #3: The VT200 is heavy (I'd put it at ~50kg/120lb give or take) and puts out quite a bit of heat.
I agree with Mejames in that when/if you demo the VTL 450s, it is imperative to demo them in triode. While tetrode is very, very good, triode can be magic. I find the VT200 sounds somewhat "hard" when compared to the 450s in triode mode. If you don't need the 400-500 watts that the VTL 450s can provide in tetrode, you might also try the MB 250s, which offer 200WPC in triode only.
Another high-power tube amp you might consider in the same price range would be the Wolcott Presence 220 monoblocks (though I've never heard the Wolcotts, whenever I see comments about comparisons between the VTLs and the Wolcotts, the VTLs always seem to come out second best). I would also recommend trying the Counterpoint Natural Progression series (even though they are less tube amps than hybrid amps). I was very impressed with the monoblocks.