i have used all three systems you speak of and they are as follows:

35mm- canon 1V with 28 1.8, 50 1.8, 85 1.8, sigma 120-300 2.8, and nikon 400 2.8 via adapter
with 35mm ive shot from tech pan, pan f, px 125, hp5, tmx 3200,

for MF- Mamiya RZ67 proii with 50 4.5 ULD, 110 2.8, and the 140 macro you have
plus-x 125, technical pan, pan f, tri-x 400, and panatomic-x...probably more but i forget at the moment

digital- canon 40d and now a canon 1d3
with the same lenses as listed with my 35mm

i englarge my 35mm negatives with a nikkor 50 2.8 and all my 6x7 negatives with a nikkor 105 5.6. the enlarging lenses are simple awesome, i see no point in getting a schneider or rodenstock APO lens unless i am trying to print 35mm 16x20 on 20x24 paper which is something i wont do because i feel thats already past the limit of 35mm...sans one particular film.

i print on ilford MGIV fiber, Adox MC110, and Arista EDU paper.

i forgot to mention, for both formats i use glassless carries and its never been a problem thus far.

ok, now on to the good stuff. i totally agree with you however there is one, and only one exception to the rule that you have come to realize and many have...and that exception is Kodak Technical pan. in 35mm, it rivals almost all non tech-pan 120 films, and in 120 format it rivals all the 4x5 ive seen except 4x5 tech pan. pan F is close but no cigar, they are very different films. so, pretend we take out technical pan and you my friend have realized the joys of medium format. a grainless print from HP5 in 35mm is unheard of, unless you print 8x10 or smaller, its a damn grainy print. you should try to plus-x 125 in your RB and youll be amazed, my prints are grainless and while i havent printed that big i have cropped the sh*t out of my images at times. i hardly shoot 35mm and when i do its for telephoto reasons or because i need quick action and its super sunny and i have technical pan on hand.

so to answer your question, as far as resolution goes, yes, i believe 35mm technical pan can match 120 HP5. smoothness and tonality- ehhh idk about that one. detail and clarity- very posssible. buuttttt, and its a big but, you are shooting at ISO 25/32/or 50 to get the same results as an ISO 400 film. and try the 50 ULD with the floating element, i think it beats my 140 macro, simply unbelievable resolution. sorry for the rant, i could go on and on about this epiphany you had, which i also had at one point.