I don't know where al this 'MTD is great sounding alone, but sucks in a band' starts from.
First of all, I'm not an MTD dealer for a living, I became Mike's dealer coz he's a great guy, and I love his Basses, and we're both New Yorkers

Well, he's upstate, and I don't even live there anymore... So anyways, what I'm saying doesn't give me anything, just saying MY Opinion and Experience.
I played with whatever amp, mixer the venue has, different sound guys, band members, etc. I used to bring my Tecamp Puma, don't have a cab, but unfortunately I have to sell the Puma, now I'm down to my MTD, a 78 Jazz and a Yamaha Silent Bass (Elec. Upright).
Sometimes I doubled, switching from Electric to Upright with the same Channel on the mixer, etc, I don't even bother changing my amp setting, and I found that especially for these occasions, my MTD 535 is a better choice then my 78 Jazz, I can switch between the two, and the sound guy doesn't even know. The 78 Jazz works well too, but the 535 is just more right.
On those gigs that I doubled, it's almost certain that I have horn(s) and a string section, with Grand Piano, THE instrument that annoys the hell out of me when the player plays too much on the lower octave, add a cello to that and you have a bad time hearing yourself, and on these gigs we never rehearse, show up, sound check for 30mins, set list check, and play. I sometimes don't even know who I'll be playing with.
And again on those ocassions, I prefer my 535, with or without my upright to switch around. For Gospel, I play in church almost every week, different churces, never bring an amp, DI whatsoever with me, the 78 Jazz and 535 is as fun, never heard people comment that they like the one better then the other. A 'real' Gospel Band I was in was about 2 years ago, I had a different MTD back then, but it's the same, everyone loves the way it sounds, that time I was carrying around an Eden WT400, no specific cabs.
So, based on those facts, I don't know where all these prejudices come from, but yeah, some players' no 1 Instrument is another's gear I'll never buy list. I remember playing Kim Stone's Roscoe and don't like it, and he told me that he can't live without it. And I never liked a P-Bass in my life
For me, if I like an Instrument, that instrument will give a level of comfort that allows me not to think of anything, and just enjoy playing, and that made my playing and hence, my sound better, I never heard someone sound bad if they play with all their harts and minds, and that made their Instrument 'sat well on the mix'.
So, just give it a shot, sorry to say, you don't need any fancy amp or DI, I've been doing it without my Tecamp, and IMO my 535 sounds even better just with any DI to the mix, the true color really shines. I'm lovin' it